WGR   Number 10   June 1991


 

Note added to the 2020 edition:
The original paper version from 1994 was printed in monospace font, with no illustrations except for the front and back covers.    It is reproduced here in a slightly reformatted version, with minor error corrections, and the covers scanned from the original. No attempt has been made to bring the material up to date; in particular, many of the publishers are out of business, most of the books and commercial games are out of print, and the addresses can all be assumed to be out of date.   (The Internet was in its infancy then, and there were no web references.  A second version which incorporates all of the additional material from WGR is planned.    An entirely new edition might be produced if there is enough interest.




Front cover : The most popular chess variant boards (left to right, top and bottom rows):

(1) the 8x8 chessboard used in orthodox chess and many variants
(2) the 10x10 chess board, popular in variants with one or two new pieces added to each side (variants played on this board are collectively referred to as decimal chess)
(3) a 4x16 ringed board, used in variants of Shatranj and modern chess
(4) the most common four-handed chess board, 8x8 with four 3x8 wings
(5) the xiang qi (Chinese chess) board -- units stand on intersections rather than squares
(6) A three-colored hexagonal board, used in several two- and three-handed variants. Hexagonal boards of other sizes are also seen.




Back cover : Seven boards with arrays (top to bottom, left and right):
 
(1) Tesche's 3-Handed Chess [611]  
(2) Petroff's (4-Handed) Chess [453]
(3) De Vasa's (Tricolor) Chess [192] 
(4) Rutland's Chess [531]
(5) Decimal Oriental Chess [181]
(6) Double Rettah Chess [208]
(7) Petty Chess [454]


Edited and published by Michael Keller
copyright ©1991 by Michael Keller
International Standard Serial Number (ISSN): 1041-0546.

   This is a special issue on chess variants (hereafter referred to frequently as CV's). Special thanks are due to the following individuals for their contributions to this issue:

Alessandro Castelli, director of AISE (Associazione Italiana Scacchi  Eterodossi), the Italian CV organization, who has regularly sent me their bulletin Eteroscacco.
Philip Cohen, inventor or many CV's and chess variants columnist for Nost-Algia, who permitted me to use material from his column, made hundreds of additions and corrections to the first draft, and sent a photocopy of his extensive notebook on CV's.
George R. Dekle, Sr., chess historian and inventor, who allowed me the use of his own extensive files, allowing me to add about 75 new listings (including more than 20 of his own invention) and clarify many others.
Patrick Donovan, keen player of CV's, who sent rules and sample games for Shoot C and Knightrider Bouncy C, traded me a copy of Lai's book on Xiang Qi (Chinese Chess), and sent a bulletin from his tournament in Progressive Circe.
Giorgio Ervetti, who provided notes on several of my Olympic Progressive Take-All games.
Marco Fabbri, chess variation expert, who added many new listings.
Malcolm Horne, games consultant to Variant Chess and organizer of British CV play under the name "Deviant Chess Week", who informed me of the week's activities, and sent a bulletin from his Postal Scottish C tournament.
G. P. Jelliss, publisher of Chessics (now replaced by Variant Chess), who sent his own classification scheme and made other helpful suggestions, and whose publications provided a great deal of information.
John J. McCallion, enthusiastic CV player, who directed my attention to a number of new games and sources of information, and sent me two of his annotated games.
David Moeser, editor of J'Adoube, the Cincinnati Chess Bulletin, who sent a large set of variations (many of his own invention) published there, as well as copies of the rare publication Chess Spectrum.
David Pritchard, game inventor and editor of Games & Puzzles, and author of an upcoming book on CV's, who sent information on a number of variants.
Mrs. Motoko B. Reece, the head buyer of the John G. White Collection of the Cleveland Public Library, who assisted me in locating many items in the largest collection of chess books and magazines in the world.
Rudolf Ruhle, who sent information on European commercial variants.
Roberto Salvadori, one of my opponents in the First Heterochess Olympic Games, who permitted me to reprint one of our Progressive Circe games, and who sent an amusing sample game of the same variant.
Sid Sackson, game inventor and collector, who gave me a guided tour of his collection and helped me locate many commercial variants.
Tiziano Sala, who sent his latest booklet of Progressive Circe games.
A. J. Stone, CV player and postal gamer, whose informal booklet on CV's was a useful source of information.
Paul Yearout, CV expert and WGR contributor, who provided additional information on several variants.
The following inventors who permitted me to include their variants:  Ralph Betza, Keith Bogart, John Bosley, Douglas Engel, Prince Joli Kansil, Alan Parr, Vladimir Pribylinec, R. Wayne Schmittberger, and Bruce R. Trone.

Table of Contents
Colophon, Special Thanks
Table of Contents
Editorial, Acknowledgement, Introduction
General Observations
Appeal For Information, Terms
Notation
General Rules, The Best Chess Variants
CV Organizations
Game News
Book and Magazine Reviews -- Shogi World, Chinese Chess, Chinesisches Schach/Koreanisches Schach, Chinese Chess for Beginners
Game Reviews -- Four-Way Chess, Fouray, Battle Chess II
CV Timeline
-----A Panorama of Chess Variants
Modifications to Forces  (Ca to Cg)
Modifications to Board  (Ch to Cm)
Modifications to Movement (Cn to Cs)
Modifications to Capture (Ct to Cw)
Other Modifications    (Cx to Cy)
Sample Games
A Challenge from Computers -- and a Challenge to Computers
Additional Pieces
Additional Rules
Inventors
Bibliography
Addresses
Index of Variations

   A year and a half after our last issue, another issue has finally appeared. What you are holding is the results of nearly five years of work, on and off, during which three further issues were published. Some may remember that this was originally announced as a supplement (like the nine page feature on hexominoes in WGR6). It grew steadily to an issue of almost triple the normal size. Regrettably it has proved necessary to count this as a double issue for subscription purposes. Any reader unsatisfied with this issue may return it to me to avoid the two-issue charge; I will also credit you with an extra issue as compensation for postage.

Acknowledgement
   Many of the chess variants listed in this issue are covered by patent, trademark, or copyright. Publishers where known are given in boldface. Inventors are listed alphabetically on page 76, along with a cross-indexed list of their games by index number. Publisher's addresses are on page 82. Commercial variants are included in the main index starting on page 85.

Introduction
   What is a chess variant? We mean a variant of 'chess' in the generic sense, not necessarily a variant of modern international chess -- including historical and regional forms. I believe it is impossible to set down hard and fast rules -- there are a number of characteristics which most chess variants have, but it is possible to find CV's which are exceptions to each characteristic. This subject is discussed in some detail in numbers 4 and 5 of G. P. Jelliss' Variant Chess.
   A typical chess variant is a board game played on a regular grid, with two or more identical starting armies, consisting of units with several different powers, including a single unit ('king') whose capture is the object of the game. The armies consist of roughly equal numbers of weak units moving in one direction by short steps ('pawns') and stronger units ('pieces') with longer ranges of movement in various directions. Turns consist of alternating moves of single units. An enemy unit can be removed from play by moving to the location ('square') it occupies ('replacement capture').
   I usually consider a game which differs from this 'standard' in one way (or perhaps a few ways) to be a chess variation. What capturing games are not considered here as CV's? First of all, games in which all of the initial units have the same power (e.g. most varieties of checkers) -- though I have included some hybrids of chess and checkers here. Secondly, games whose main objective is completely different from chess (e.g. Racing Kings, in which the object is to move one's king to the eighth rank). Thirdly, games in which capture is not present. But games in which the object is capture of some defined portion (perhaps all) of the opposing army I have classified here as CV's. We will meet some borderline cases, however, in the Panorama.
   The field of chess variants (or variations) has also been referred to as unorthodox chess, heterochess, deviant chess, or fairy chess (though the latter term usually emphasizes problems). International chess (the standard form in most of the world) is referred to herein as orthodox chess (orthochess for short). In general, we will deal very little with problems in this issue.
   I hope that errors in this issue prove to be minimal. I have cross-checked rules in multiple sources wherever possible, in cases of conflict relying on those references known to be very reliable or authoritative -- the original published rules are preferred in all cases to second-hand accounts, some of which contain many errors. I would appreciate hearing of any mistakes. Some variants had to be left out due to lack of information. E.g., most unpublished variants were omitted unless I was able to give complete rules (usually directly from the inventor). The past two years have been extremely busy ones in CV activity. See Game News for a summary of some of what has taken place.

General Observations
   Many orthodox chess players consider chess variants to be unworthy of anyone's interest. There are several reasons why this is not so. First, modern chess itself is one of a long line of variations of early forms of chess which began in India or China. Were it not for the innovations of earlier players, the modern queen and bishop would not exist. Secondly, standard chess is by no means a perfect game, incapable of improvement. Thirdly, many players who have played variants have found their play at orthodox chess to be improved (progressive chess and shogi have been cited in this regard).   Joseph Boyer, in his classic books on CV's, stated some of the reasons for devising chess variations: (1) to force players to rely on their own resources instead of memorized opening analysis, (2) to make draws less frequent, (3) to create shorter games, (4) to create more complex games with a greater number of combinations, (5) to allow more than two players to play, (6) to permit handicap games between players of different abilities. A later essay (A Challenge From Computers...) will present some wild speculation on the possibility of a modified form of chess eventually replacing the present game as standard.
   I have noticed while researching this issue that inventors are, by and large, far more imaginative in thinking up new variations than in finding good names for them.  Many names tend to be vague and undescriptive, and some names are used over and over again, with minor variation at best. On the other hand, there are some excellent names for variants; a few of my favorite names are Alice C, Avalanche C, Incredulon, Parallel Time-Stream C, Survival of the Species, and Transportation C. I have not hesitated to create substitute names to more clearly describe some variants, or new names for unnamed ones.
   Frequent references will be found in the text calling one variant a forerunner of another, or describing one game as similar to another.  This does NOT imply that one game was derived from another; many ideas have appeared several times independently without their inventors having knowledge of similar games. When a bibliographic source calls a game by an alternative name, that source is listed under the standard name only, but with the alternate name in brackets to make it easier to find the reference. See Pre-Chess for an example, which is called Meta-Chess in Schema 1.
   All names of specific variants are capitalized. Names in lower case letters (e.g. conversion, double-king), which may be the same as variant names, are generic names referring to families of variants.
Cross-reference page numbers are not given in the Panorama -- see the Index instead. Games are frequently be referenced by an index number in brackets [23], referring to the alphabetical Index, instead of by their full names.
   The rules given herein are, where available, the official rules of NOST or AISE, depending on which organization first adopted a particular variant (see chess organizations). In some cases they differ slightly from the original published rules -- a variant needs to be tested in play before determining whether improvements need to be made in the rules.
Appeal for Information
   David Pritchard is writing a book to be called The Encyclopedia of Chess Variants, expected to be published in 1992. He is anxious to obtain details on as many different variations as possible. Readers knowing of variants not included here may send details to Mr. Pritchard at the address listed in back, or to WGR, where they will be forwarded to Mr. Pritchard.

Terms
   In general, we follow standard chess terminology and notation.
Absorption -- the addition of a captured unit's power to the capturing unit (see Cw1). Compare mutation.
Array -- the arrangement of units at the start of play. 
Cannon move -- a move which passes over a single occupied square (containing a unit of either color, called a screen) before landing in a square which is either vacant or occupied by an enemy unit (capturing the latter). The moving unit may cross any number of vacant squares before or after the screen. The cannon in xiang qi (Chinese C) moves in this way only when capturing, while the cannon in changgi (Korean C) makes all of its moves thus -- see section Cg3.
Capricorn -- a form of capture in which every enemy unit adjacent to the landing square of a moving unit is captured (see Cu4).
Citadel -- one of the extra squares added to the board in a few variants [135,548,602]. If a king reaches the citadel on the enemy side of the board, the game is drawn. Compare thronesquare.
Conversion -- the transformation of a captured enemy unit into a friendly unit of the same species (see Cv1). If capture is by replacement, the captured unit may be relocated or placed in a reserve.
Custodian capture -- a form of capture in which a unit moves to a square adjacent to an enemy unit, with a friendly unit in the square immediately beyond, either diagonally (e.g. a2a3 with enemy unit at b4 and friendly unit already at c5) or orthogonally (d4e5 with enemy unit at f5 and friendly unit at g5). Moving to a square between two enemy units usually has no effect (but see Scaci Partonici). Variants using this form of capture are classified under family Cu3.
Demotion -- the replacement of a unit by one of a species of lesser power (see Cv4), usually by capture (but see [23, 166]). Compare promotion.
Doublestep -- the two-square advance of a pawn (normally from its initial position).
Drop -- the placement of a unit from the reserve onto a vacant square in place of a regular move.
En passant (abbreviated e.p.) -- the capture of a pawn which has just advanced two (or more) squares by an enemy pawn moving to a square it passed over. This may be eliminated or take on different forms in some variants (e.g. Berolina C).
En prise -- French term meaning under attack; subject to capture.
Expose (a king to check) -- to put a king in check either by moving it directly, or by moving a unit belonging to either player.
The 50-move rule -- if fifty consecutive moves are played by each player without an irreversible move (capture or pawn advance), either player may claim a draw. In some progressive variants, this has been changed to 10 series (5 by each player).
Foolsmate -- a very short checkmate (not necessarily of the shortest possible length), often showing some characteristic of the game, such as the vulnerability of f2/f7 in orthochess.
Grasshopper -- the most popular unorthodox piece in fairy chess problems; it makes (capturing or non-capturing) cannon moves diagonally or orthogonally, but must land in the square immediately beyond the screen. A famous problem by Valeriu Onitiu demonstrates its movement (48/5gPp/5K1k; white mates in six by 1 g3 Gh4 2 g4 Gf4 3 g5 Gh6 4 g6 Gf6 5 g7 Gh8 6 gxh8=G#).
Landing square -- the square where a moving unit ends its move.
Longleaper -- a piece which captures an enemy unit by leaping over it to a vacant square beyond, passing over any number of vacant squares before and after the captured unit (as the king in international checkers, but usually diagonally or orthogonally). It is found in Ultima as well as several variants in class Cg4.
Main diagonals -- the two longest diagonal rows of squares, running from corner to corner of a square board (on an 8x8, the main diagonals run from a1 to h8 and from a8 to h1).
Mutation -- the transformation of a capturing unit into the same species as its captive, i.e., replacing its own power with that of the captured unit (see Cw1 and [66]). Compare absorption.
Nightrider -- the most popular unorthodox rider (q.v.), which makes one or more knight moves in a straight line (e.g. from b1 to c3 or d5 or e7). It is slightly stronger than a rook.
Promotion -- the replacement of a unit by one of a more powerful species.  In most variants, pawns reaching the enemy back rank may be replaced by a piece of any desired species. In shogi (Cc3) and some other CV's, nearly all units can promote. Compare demotion.
Push -- the advancement of an enemy pawn in Avalanche (see Cr1); the movement of enemy units away from a friendly unit (see Cu5).
Removing check -- getting out of check in any possible way (moving the checked king, capturing (or dislodging in some variants) the checking unit, or interposing a unit onto the line of attack).
Reserve -- the set of captured enemy units which can later be re-entered as friendly units (see Cc3, Cv1).
Rider -- a piece which makes a series of one or more leaps (or single steps) in one direction, blocked by a friendly unit or board edge. The normal riders are bishop (fers-rider), rook (wazir-rider), and queen.
Rifle -- capture at a distance, removing an enemy unit which could be captured by replacement, without moving the capturing unit (see Cu2).
Robado (bare king) -- capture of all enemy units except the king.
Royal-- a unit subject to check, whose (imminent) capture wins the game.  A royal unit may not be moved into, or left in check. In orthodox chess, only the king is royal, but in some variations (see sections Ce, Cx3/4) other units are royal instead of, or addition to, the king.  In take-all (Cx1) and giveaway (Cx2) variants, no units are royal.
Screen -- a unit which a cannon hops over in making its move.
Sequence -- a series or part of one, during which every friendly unit (except those blocked or pinned) moves (see [222],Cn3).
Series -- a set of consecutive moves made by a player in a single turn (see Cn).
Shortleaper -- a piece which captures an adjacent enemy unit by leaping over it to the vacant square immediately beyond (as the king in Anglo-American checkers (draughts), but usually in any diagonal or orthogonal direction). It is found in Damate and other variants in section Cg4.
Species -- a type of unit (the orthodox species are king, queen, rook, bishop, knight, and pawn).
Squares -- cells of the playing board, even on boards which are hexagonal, round, three-dimensional, etc. In some oriental chesses, the 'squares' are actually rectangular.
Stalemate -- a position in which the player to move has no legal move (in multimove variations, stalemate can also occur when a player cannot finish his entire series of moves). Stalemate is usually a draw, but in some games [10,383,384,547,671] it is a win for the player who puts her opponent in stalemate. In most forms of Giveaway, it is a win for the stalemated player.
Starting square -- the square where a moving unit begins its move.
Take-all -- any game in which the objective is to capture every enemy unit. Kings are non-royal, check does not exist, and kings are captured like any other unit (see Cx1).
Thronesquare -- the starting square of the king (e1/e8 in orthochess); it serves as a secondary goal in some variants (see Cx6) -- a king which reaches the enemy thronesquare wins. Compare citadel.
Triplestep -- a three-square pawn advance, sometimes permitted in 10x10 variants.
Units -- Pieces and pawns collectively.

Notation
   Everything has been done in this issue to save space...   Standard algebraic notation (files lettered a-h left to right, ranks numbered 1-8 from White's end to Black's) is used, expanded as necessary (including letters i and j) to encompass different boards, even irregularly shaped ones such as the four-handed board on the cover -- the lower corners of the south wing are designated d1 and k1). In three dimensional chess, the level (height) of a cell is indicated by a capital letter; e.g. on an 8x8x8 board, cells run from Aa1 (bottom level) to Hh8 (top level). A square or rectangular region of the board is designated by two letters and numbers specifying its corners. The center 2x2 region of the 8x8 board is designated de45. Rectangular board sizes are always given as number of files first (10x8 means 10 files and 8 ranks). We use the standard symbols + for check, and x for captures; we denote checkmate by #.
   The four edges of the board are sometimes designated by the compass directions North, South, West, East (N/S/W/E), indicating the 8th rank/1st rank/a file/h file respectively. Similarly the corners may be designated NW/NE/SE/SW. Players in a four-player game are referred to as N S E W on a winged board, NW NE SE SW on a square board.
   The standard method of showing a board position without the need for a printed diagram is Forsyth Notation. The contents of each square are listed, rank by rank, beginning with the eighth rank (moving left to right on each rank). White units are denoted by capital letters, Black by lower-case letters (in four-handed arrays, one pair of teammates are shown in capitals -- one in boldface, the other in lowercase (N S w e or NW SE sw ne)). One or more consecutive empty squares are denoted by a number. Slashes separate each row.  Arrays in the Index are preceded by the board size (8x8 omitted).
   An entirely empty rank is denoted .../8/.... Several consecutive empty ranks are sometimes denoted /16/,/24/, etc. The fool's mate (1 f3 e5 2 g4 Qh4#) would produce the board position rnb1kbnr/pppp1ppp/8/4p3/6Pq/5P2/RNBQKBNR. A solid row of like units (usually pawns) are denoted with a number in parentheses indicating the quantity, and $$ (for Black) and $ (for White) denote the normal row of pieces ($$ = rnbqkbnr, $ = RNBQKBNR). The orthodox array is then: $$/p(8)/32/P(8)/$. This may also be abbreviated $$/p(8)/32/..., the ellipsis indicating that the White end of the board is the mirror image (or the reversed mirror image if followed by <>). Three-dimensional arrays are listed top to bottom, with levels set off by double slashes.

General Rules for Chess Variations
   For variants herein, unless otherwise stated, the rules of chess (including castling, en passant capture, promotion, etc.) apply, as well as the following additional rules. Castling is prohibited if the king is in check, king or rook have moved, or any intervening square is checked or occupied (the rook may cross attacked squares). Check is normal and the objective is checkmate. Pawns may promote to any non-royal piece present in the array (and no others). Pawns returned to their initial (usually second) rank, by whatever means, are permitted the same moves (in particular doublestep) allowed pawns which have not moved from that rank; this follows a general simplifying principle of allowing all possible moves to be determined from any position without knowing the past moves of the game. In arrays where the pawns start from more than one rank, intial privileges (i.e. doublestep) apply equally to all pawns.  In variants with obligatory capture [e.g., 256, 392, 553], when more than one capture is available, the capturing player can choose to make any capture. When unorthodox capturing methods are introduced, we explicitly say whether they are in addition to or in place of replacement capture. A unit which cannot capture in a given situation does not check the enemy king (a notable exception is in U-Chess, where seventh-rank pawns check enemy kings on the 8th).

The Best Chess Variants
   From an informal poll I took of a few enthusiasts, published literature, and NOST records of CV games, the following games might be considered among the best variants (in alphabetical order). Thanks to Phil Cohen, John McCallion, Wayne Schmittberger, and Paul Yearout.
   It is interesting to note that, except for the regional games shogi and xiang qi, nearly all of the most popular variants require only ordinary equipment (8x8 board and 32 or fewer orthodox units) -- over half of the variants in the Index meet this criterion. Ultima requires a set in which one rook can be inverted (as in most standard Staunton sets). Chessgi requires a second set of units for unequal exchanges.
Avalanche Chess -- invented in 1977 by Ralph Betza, it has gained popularity with remarkable speed -- it is currently the most popular CV in NOST, and was the U.S. choice to play in the First Heterochess Olympics.
Berolina Chess -- Phil Cohen says : "easy to learn (takes 15 seconds) and far-reaching in consequences". Combines with Grid C to improve the latter game and produce the NOST's most popular combination game.  It is less drawish than orthochess -- pawns are stronger in the endgame.
Chessgi -- invented in 1964 by Ralph Betza, this is one of several adaptations to orthodox chess of the shogi idea of re-entry of captured units. Another Olympic game, chosen by the U.K. team.
Dynamo Chess -- one of the best among the complex games.  It is the most complex game for which we will give full rules here.
Extinction Chess -- a very recent variation, it has become fairly popular in NOST, partially because it is similar enough to orthochess to draw in chess players who would not normally play CV's. Its variety of targets allow for a wide range of tactical plans.
Giveaway Chess -- extremely popular in both AISE and NOST, and well-established even among orthodox players who disdain most variants.   Another popular component of combination games. Games are frequently short because of long sequences of forced moves. Chosen by the second of three Italian teams in the Olympics.
Knight Relay -- NOST favorite gaining adherents elsewhere, particularly in AISE tournaments.
Progressive -- In its Italian and Scottish forms (very similar) it is by far the most popular (non-regional) CV ever, topping the lists of most games played in both NOST and AISE. Postally it is ideal because games finish quickly. The English variation, which allows more long range planning, is held in very high regard. Progressive has also given new life to variants (Absorption, Bughouse, Circe, Kamikaze) that don't work very well alone.
Shogi (Japanese Chess) -- the consensus favorite among national variants; many players have declared it superior to orthodox chess. There are several variants of shogi itself -- Wa shogi, Chu shogi, and Tori Shogi are also considered quite good. There is now considerable literature in English.
Ultima -- despite Robert Abbott's reservations (see WGR8), it remains one of the top games among players who enjoy very complex CV's. It has in turn given rise to more complex games.
Xiang Qi (Chinese Chess) -- the other important regional variant, a fine tactical game. Ishi Press claims in its advertising that xiang qi is the most popular game in the world. It is perhaps more similar to western chess than shogi is to either game. There is a considerable literature in Chinese; lately there are an increasing number of books and magazines in English (though still less than for shogi), playing sets, and computer opponents available (see Game News; Reviews).

CV Organizations
AISE (Associazione Italiana Scacchi Eterodossi) -- formed in mid-1970's.  Conducts extremely active play in a number of variants, especially progressive ones (lately many NOST games are being added to its repertoire; AISE even seems ready to bravely abandon years of opening analysis of Marseillais C for the superior Balanced form). Provides ELO-style ratings for the major variants. Publishes a quarterly magazine (32+ pages), Eteroscacco. AISE has also published a number of bulletins for various tournaments and now offers a collection of over 5000 games of Italian Progressive C, available in either printed form, or on floppy disk. The Italian players have studied and named many of the openings in Progressive.
Ishi Press International -- commercial company which sells books, equipment, and computer software for shogi and xiang qi. Made its name in the go field (in which it is still preeminent), and expanded into other oriental games in the past few years. Distributes mamy of the commercial programs to play go and chess variants (including Xian, Distant Armies, and the just announced Shogi Master). Publishes a quarterly 20-page magazine, Shogi World.
NOST (Knights of the Square Table) -- formed 1960. Originally a postal chess club, it has gradually branched out into chess variants (as well as other games). Conducts tournaments and matches in a large number of variants, and holds an annual convention (NOSTventions will be referred to herein, e.g. NV'88). Publishes a (currently) bimonthly 28 page magazine (of which several pages are devoted to CV's), NOST-Algia. The yearly schedule now contains over 30 different CV tournaments.
The Shogi Association -- Published 70 issues of the renowned Shogi Magazine between 1976 and 1987. Founder George Hodges still sells books, magazines, and equipment for shogi and eight of its variants.
TC/Lawrence -- formed 1981. Publishes Transcendental Chess, a 16-page monthly which conducts postal play (including prize tournaments) in Max Lawrence's variant (described in section Cb1).
The U.K. Chinese Chess Association -- formed 1989. Publishes a bimonthly 16-page magazine, Chinese Chess.
A group of CV enthusiasts in the United Kingdom, led by G. P. Jelliss and Malcolm Horne, are organizing 'Continuous Correspondence Tourneys' in various chess variants. This may eventually lead to an informal CV organization in the U.K., analogous to NOST and AISE in the U.S. and Italy. Jelliss' quarterly magazine Variant Chess, which in less than two years has joined the ranks of the leading CV magazines, would serve as a natural forum for such an organization.

NOST Top Twenty (alphabetical):
 Alice C     [12] Dynamo C      [215] Scottish C    [537]
 Avalanche C   [40] English Progressive [222] Shogi      [552]
 Berolina C    [53] Extinction C    [230] Transportation C [628]
 Berolina Grid C [54] Giveaway C     [256] U-Chess     [643]
*Cheskers    [103] Grid C       [269] Ultima      [646]
 Chessgi     [110] Knight Relay C   [328] Xiang Qi     [676]
 Compromise C  [145] *Racing Kings    [496]
* I classify Cheskers as a CV and Racing Kings borderline at best; NOST calls Racing Kings a CV and Cheskers a checkers variation, which falls under NCG -- Non-Chess Games).
Games on the annual NOST tourney schedule:
 12,40,44,53,54,103,110,145,169,215,222,230,256,269,286,322,328,333,374,421,434,496,510,537,542,552,628,635,643,646,671,676.
NOSTvention tourneys: [40] 1979/1985(a simultaneous exhibition given by Paul Yearout)/1987/1989, [470] 1980, [537] 1982, [328] 1983, [540] 1984, [230] 1986, [222] 1988, [635] 1990.
The AISE annual championships: 44,76,256,309,473,474,476.
Other games include: 40,40/309,47,53/309,77,92,97,110,141,145,149,169/309,204,215,222,230,256/370,307,308,328,346,370/476,406,434,475,496,542,547,552,602,628,643,646,676.
Game News
   The  First Heterochess Olympic Games began in October 1988, involving 40 players from 7 countries. The tournament, the first international multi-game CV postal competition, was co-sponsored by the AISE in Italy and NOST in the U.S. After a slow start and a few players dropping out, the games got underway in earnest. Each of eight teams (U.S., Canada, U.K., New Zealand, Czechoslovakia, and three from Italy) chose one CV to play; these are Italian Progressive, Progressive Take-All, Progressive Circe, Mutation Chess (invented especially for the tournament by John E. Bosley of New Zealand), Chessgi, Marseillaise Chess, Giveaway (Losing) Chess, and Avalanche Chess. The first four variants are progressive (white plays one move, black two, white three, etc.), and generally only last 6 to 12 moves. The majority of the progressive games (and some of the others) have been completed; I finished my entire slate of 34 games (for the U.S. team) some time ago. I include a few in the Sample Games section.
   Super Chess, Inc. is sponsoring a tournament in Super Chess (reviewed in WGR7), now being conducted through NOST. All registered owners of the game were invited to participate. Super Chess will divide $1000 among section winners, probably the largest prize fund ever for a CV competition. It has drawn 37 entries, the largest CV tournament in NOST history. We will report the results in due course.
   Tiziano Sala, one of the leading players in AISE, has published a new booklet containing over 150 transcripts of Progressive Circe (AISE abbreviation CRPR), from three recent tournaments, including the First Heterochess Olympics. The games in each tournament are sorted by opening, which saves space and helps players study the openings. The booklet is 39 pages, mostly in Italian, but with enough English to allow anyone who can read English to follow it. The notation used is algebraic with the Italian initials for the pieces (KQRBNP ==> RDTACP). The booklet was sent to all players who played in any of the tournaments covered; others can write to AISE for information on obtaining this, any of Sala's previous seven bulletins on Progressive Circe, or other AISE publications (including the Progressive compendium).
   I also received two bulletins from recent British postal tourneys:
Malcolm Horne's one-page bulletin containing twenty games from a five-man double round-robin in Scottish Progressive C (I can provide copies to interested readers), and Patrick Donovan's two-page bulletin from a four-man double round-robin in Progressive Circe (the games from the latter were reprinted in Eteroscacco 48). Horne is also publishing a newsletter on Xiang Qi, which I have not seen yet.
   A recent CV product in the computer software field is Distant Armies, A Playing History of Chess. This is a set of programs which play thirteen different historical and regional variants of chess: Chaturanga, Shatranj, Burmese C, Xiang Qi, Byzantine C, 3 forms of Mediaeval C, Courier C, Turkish C, 2 forms of Decimal C, and Los Alamos C. At last report, the package was available only for the Commodore Amiga computer, and I have not been able to evaluate it. If any reader has an Amiga and would like to review it for WGR, I will arrange to have the publisher, Eagle Tree Software, send a copy. The package is also being distributed by Ishi Press International.
   Ishi Press International has announced that a new program called Shogi Master will be released this year. This will be the first shogi-playing computer program commercially available in the U.S.  We will try to have a review as soon as possible.
   One of the two games of postal xiang qi being played between Paul Yearout and the program Xian (published by Leong Jacobs; see WGR8) has ended in an agreed draw. We will have the game score with comments by Paul in the near future.
   The Vietnamese American Chess Association was formed in 1990 to popularize Chinese Chess among Western chess players. They offer a laminated board, cardboard pieces, and a four-page instruction leaflet including five example games and two mating problems, all for $3.00 postpaid in the U.S. Recommended as an inexpensive introduction to xiang qi. The pieces use western symbols (standard symbols for KBNRP, pictures of cannons and guards), and the instructional material is aimed at orthochess players. The founder, Vu Van Dong, is also trying to get some Chinese books on the game translated and published in English.
   There is also a California Chinese Chess Asociation, established in 1989 by Scott Yen, which is selling sets in both modern and traditional styles. They also plan to publish books in English, and are also hoping to develop U.S. players able to compete in international events.
   Xiang qi is also one of the games covered in a Swedish magazine, Bradspelaren (The Boardgame Player), covering the history and strategy of various board games (Abalone, Othello, Renju, Pente, xiang qi, and go).  Information may be obtained from the publisher, Bengt Ericson.
   Mirko Babic, a Yugoslavian games enthusiast, is organizing postal tournaments in a variety of board games, including Hexagonal Chess (Glinski), shogi and variants, and a game blending chess and checkers. Cost to enter a 5-person section is $3.00 (overseas payments in cash).  Mr. Babic has also published several volumes of a collection of 10x10 checkers games, sorted by openings (more next issue).
   Wayne Schmittberger has written articles on chess variant design, describing his games Generalized C and Wildebeest C and how he invented them (the latter also has some opening analysis). Information on these two articles as well as details on his many other variants can be obtained directly from him at the address in the back. Rulesheets for CV's they have invented (especially where designated %%% in the Index) are also available at nominal cost from Philip Cohen, George R. Dekle Sr., and Bruce Trone (in most cases these can also be obtained from WGR).
David Moeser has available a 51-page package of CV articles from Cincinnati-area publications at $5.00 postpaid. This includes everything with J'A listed as a reference in the Index.
   Games magazine is publishing again after more than a year out of business. The new owner is Bits and Pieces, which produces and sells puzzles (especially jigsaws) and games by mail. The new addresses are listed in back.

Magazine and Book Reviews
Shogi World -- 20 page (26x18 cm) quarterly, jointly published by Ishi Press International and the Japan Shogi Federation, $12 yearly from Ishi Press.
   Eight issues have so far appeared. The emphasis is on instruction. The first issue has three pages of detailed rules, condensed to one page in number 2. Number 2 has information on draw rules. Editor Glyndon Townhill, a British expert amateur, is currently writing two columns, "Easy Checkmates" (tsume-shogi endgame problems, in which each move must be check), and a series on openings (volume 1 covered "Castles and Castling", volume 2 covers the "Climbing Silver" opening). Issue number 4 began a series on hisshi (endgame problems which begin with a non-checking move). Each issue contains an annotated game and news from the Japanese professional ranks and other tournaments. Diagrams are currently being presented in westernized form, but guides to Japanese diagrams have appeared. It is not clear yet whether the magazine will eventually change to Japanese diagrams (the annotated game in the current issue uses them). This appears to be a very good magazine for beginners and intermediate players.
Chinese Chess -- Newsletter of the UK Chinese Chess Association, 16 page (21x15 cm) bimonthly, edited by Malcolm Chandler, 10 pounds (U.K.) per year payable to the UK Chinese Chess Association
   So far I have only seen Number 1 of this publication (March/April 1989). It contains news, the UKCCA constitution, Chinese-style notation, a few endgame problems, a bit of opening analysis, and no less than eight annotated games, with players ranging from Chinese grandmasters to British amateur experts to commercial programs!  The diagrams are Chinese-style with Arabic numerals. There is some emphasis on (mostly informal) postal play. This is a good debut, and again looks to be useful for beginners (like me) and intermediates. Mr. Lai, the general secretary of the UKCCA, published a small book on xiang qi openings in 1987 (see bibliography).
Chinesisches Schach/Koreanisches Schach -- David Wurman, 345 pp., paper, 1991, Verlag Harri Deutsch, ISBN 3-8171-1166-5, 53.00 DM (German -- about $35 U.S.) including postage.
   This brand-new book in German contains a wealth of information on xiang qi (Chinese chess) as well as its Korean cousin changgi. There are 232 large diagrams using algebraic notation and modern international symbols for the pieces, as well as 55 interesting illustrations. Though the large text sections are not much help if you don't read German, the game transcripts and problems are easy to follow -- you need only learn a few German initials for the pieces. Diagrams are provided showing the moves of the pieces, basic checkmates and combinations, openings, and foolsmates (e.g. 1 Ch3h5 e7e6 2 Cb3e3 c7c6 3 Ce3xe6 Cb8b6? 4 Ch5e5#).  There is a substantial section on opening variations, a complete system of handicaps, 12 annotated games each for xiang qi and changgi, and almost 100 xiang qi problems ranging from useful checkmates to frivolous ornamentals. A section on xiang qi variants shows early forms of the game as well as variants for three, four, and even seven players.  Scattered throughout the book are addresses of xiang qi contacts in various countries.
   The section on Korean chess is only 58 pages, but includes a five-page comparison of differences and similarities between the two games, as well as sample games and examples. The rules for changgi given in other Western sources appear to be incomplete; this may be the only fully reliable guide outside the Orient.
   Included are cardboard pieces for both games and a two-sided playing board. The book is expensive, but worthwhile (especially if you read German) for anyone with a strong interest in xiang qi or any interest in changgi.
Chinese Chess for Beginners -- Sam Sloan, 181 pages, paperback, 1989, Ishi Press International, ISBN 0-923891-11-0, $9.95 plus $1.50 postage
   This is an excellent guide to xiang qi, written by a Western expert in the game. Sloan's book is much easier to read than Lau's book (reviewed in WGR7), giving clear explanations of the basics of play, and relying less heavily on unannotated opening and endgame variations (in retrospect, Lau's book may be too difficult for the absolute beginner).  Sloan also uses Chinese-style notation (instead of algebraic), but the diagrams use English initials instead of Chinese characters.   After an introduction to present day play in Chinese Chess (a Hong Kong businessman has offered a half million dollars to the first non-Chinese player to win a major tournament in xiang qi), Sloan covers the rules of play, basic checkmates, the opening, general strategy, how to use each piece, and the endgame. Several sample games are annotated in detail to show the reasons behind the moves. He finishes with chapters on current players, history of the game (a very controversial but interesting chapter), and how to find opponents (including computer programs and human clubs).   The book is entertaining to read throughout, ideal for instructing the beginner, and a good companion to Lau's Chinese Chess.

Game Reviews

4-Way Chess -- invented by Stephen R. Stockman, published by Taurus Games, 1988, write for current prices.
Fouray -- invented by Jack Quinn, published by Fouray Plus, 1986, write for current prices.
   Four-handed chess has proved a popular variant for over two centuries. Verney's Chess Eccentricities, published in 1885, describes a large number of them. The White collection catalog in Cleveland lists more than 20 different books on four-handed chess. It is therefore not too surprising to see two new commercial publications of four-handed chess (see also Chessnuts, reviewed in WGR7). Like most four-handed chess games, both games are played on an 8x8 board with four 3x8 wings.
   4-Way Chess is a fairly conventional four-handed variant, but Stockman has devised an excellent set of rules, eliminating some of the poor features of other four-handed CV's. Pawns promote at any board edge they can reach -- a pawn from the South army can promote not only at the far ends of the west and east wings (by repeated capture), but at the north ends of those wings (abc11 and lmn11) and the north end of the partner's wing (d14 to k14). Another good rule is that the army of a checkmated king is entirely removed from play, giving players stronger incentive to checkmate an opponent and eliminating complicated rules for relieving mate. The nicely printed rulebook (available separately) includes examples (including openings and a few short checkmates) and advice on tactics, as well as rules for a four-handed checker variant played on the same board.
   Fouray is a very unusual four-handed variant. Partners control adjacent armies (North/West vs. South/East), and the object is for each team to checkmate the 'Great Kingdom' (North or South) of the opponent. West and East are thus reduced to supporting roles, though still subject to check and mate (which immobilizes their forces).  A good variant with players of different abilities (let stronger players play North/South).
Battle Chess II: Chinese Chess -- programmed by Greg Christensen and Scott Bieser, published by Interplay Productions, 1990, IBM, $49.95.
   This is a new xiang qi program from the makers of the popular chess program Battle Chess.  Like its predecessor, Battle Chess II has an elaborate 3-D graphics display, with animated pictures of kings, chariots, cannons, soldiers, etc. The pieces can actually be seen to move along the board, and the capture sequences are humorous (e.g. when a chariot captures a knight, it turns into a dragon and eats the poor knight!).  Two-dimensional views (with Chinese symbols or English initials) are available at any time. Options include saving games, setting up your own positions, retracting moves, and playing by modem. Nine playing levels (with preset thinking times) and an unlimited thinking time option are provided. The 32-page manual provides details on program options as well as a very good introduction to the game (a brief history, rules, strategy, and five sample games). I have played a few games against the program, and it won fairly easily at level 3 (30 seconds per move). This is the third xiang qi program to be commercially available in the U.S., joining Xian and the Chinese Chess portion of Distant Armies. (There are at least two versions in the U.K. -- Novag Chinese Chess, from Eureka Electronics, and Ogre for the Spectrum 48K by Allan Brown). I hope to match Battle Chess II against Xian and/or some experienced human players soon -- watch WGR for results.

A Chess Variation Timeline
1617 -- Pietro Carrera invents a 10x8 variant introducing combined knight-rook and knight-bishop pieces (which we will call chancellor and cardinal). These pieces are used in dozens of later variants, including very similar 10x8 games by Bird and Capablanca.
1683 -- Francesco Piacenza devises a decimal variant, arciscacchiere (Arch C [30]) including all of the modern pieces, plus the fers and a piece known today as the squirrel (which can leap to any square two squares away, combining knight, alfil, and dabbaba).
1722 -- Filippo Marinelli invents the first modern 3-handed variant, played on an 8x8 board with three 3x8 wings. JENO cites a reference to a four-winged board in 1664; my earliest reference is 1779. (See the reviews of Four-Way and Fouray, and section Cy2).
1828 -- Tori Shogi, the newest and smallest of the classical shogi variants, is invented by Toyota Genryu, disciple of shogi champion Ohashi Soei. The first western minichess, Petty C, appears in 1930.
1907 -- Ferdinand Maack publishes Raumschach (Space C), the first known three-dimensional variant. Originally he tries 8x8x8 and other sizes before settling on a 5x5x5 board. Several books and a magazine are written about it, though it is little played today.
1912 -- Siegmund Wellisch invents the first chess variant played on a board composed of hexagons. It is played by three players on an order-6 hexagon (as shown on the cover). In 1929, Baskerville devises a two-handed game on a roughly rectangular board.
1921 -- W. B. Seabrook invents Rifle C, the first CV without replacement capture.
1926 -- Edmund Nebermann invents the Berolina pawn, reversing the Western pawn's capturing and non-capturing moves. Initially used in problems, it later becomes a very popular variant, alone and in combination.
1952 -- V. R. Parton begins his prolific career as a CV inventor with his first published creation, Rettah C.
1957 -- Mannis Charosh creates Relay C, from which he derives (in 1972) the extremely popular Knight Relay C.
1961 -- Robert Abbott conceives of a variant, eventually known as Ultima, in which each piece has a different form of capture, mostly borrowed from older board games. His original piece called the coordinator,  however, inspires Ralph Betza to create the family of variants called co-chess.
1977 -- Ralph Betza invents Avalanche C, which becomes one of the most popular CV's in a remarkably short time.

A Panorama of Chess Variants
   This section follows an expanded version of the chess section of the Taxonomy of Games published in WGR1 and amended in WGR3, and is based partially on schemes and ideas by Joseph Boyer, Bob Bruce (Nost-Algia 115, Nov.1969), George R. Dekle Sr., Marco Fabbri, G. P. Jelliss, and Donald L. Miller. Many chess variations have changes in more than one category. In each case, a decision has been made as to which change is the most significant, and the variant is classified in that way. For example, most 10x10 (decimal) variants are classified under new pieces rather than new boards. 'Chess' is usually omitted or abbreviated here. Other details (array, general rule changes) are found in the Index.

Ca -- Fixed initial position
  Ca1 -- Equal armies
   Many games have been proposed using alternate arrays and standard, reduced, or augmented armies of orthodox units. Reversed Minor Pieces, advocated by Capablanca when he was World Champion, is perhaps the best known variant with a modified array, but it has the same drawback pointed out for certain 10x10 variants (see Ch1). Also, the b and g pawns are hard to defend, and it is awkward to develop knight and bishop together.    Diamond C is a variant with the array diagonally aligned. White pawns singlestep diagonally northwest, capturing one square orthogonally north or west, promoting on the 8th rank or a file. Black pawns similarly move SE and capture south or east, promoting on 1 or h. Adjacent pawns can be moved in alternation with the more advanced one always guarded by the other. The board may be turned so that h1 points to White and a8 to Black. Lewis' C is a variant array of Diamond C (a1 and h8 point to the players; pawns move NE/SW). Diagonal C uses an array of a different shape; White pawns promote from a5-a8-d8, Black e1-h1-h4.  Citadel is a commercial version from 1940.
   In Double Queen C, both players start with two queens on their normal starting square (d1/d8). The queens move individually, and multiple occupancy (see Cp1) is not allowed after one queen leaves the starting square. If an enemy unit enters the queensquare before either queen leaves, both are captured. A medieval variant using the same idea is Short Assize C (see Cc1).
   The Little Game is listed as a variant in several books, but is in fact merely an endgame study, known to be a win for White (analysis can be found in most books covering the chess endgame, e.g. OCC).
   In Patt-Schach, both sides start in stalemate, and each player on her first move may move any unit to any vacant square (i.e., without capturing). Play than proceeds normally; a pawn may not advance to its eighth rank unless there is at least one lost piece to promote to. Upside-Down C is a similar game.
   Described in the index (with arrays and minor rule changes) are: 8, 138, 157, 240, 250, 331, 441, 447, 518, and 654.

  Ca2 -- Unequal armies
   Eight Pawns and Two is a variant in which White has only her king and pawns against a full Black army. White, however, makes two moves per turn as in Marseillais C (Cn1). White can move into check or remain in check on her first move (even moving her king adjacent to the enemy king or capturing a guarded unit with it), but must be out of check after her second. Check given by White on her first move is ignored if removed by her second. Both sides promote normally and the object is checkmate. En passant is normal and Black can use it to nullify a capture by a White pawn which doublesteps on its first move and captures on its second.  White is said to have an advantage (NJENO offers good advice on Black tactics).
   Variations of this game include Monster C (colors reversed, Black can only move one unit per turn (the moving unit can move twice unless it is a promoted piece)) and One-Two (White has only four pawns which do not promote, the White king can move through its own pawns, White's object is to capture the Black king as in Doublemove C (Cn1) -- the Black king must stay three moves away from White king and pawns, Black mates normally). JENO also cites a variation in which Black has no pawns (White cannot check on her first move). The oldest known version of Eight Pawns and Two was a medieval Shatranj problem (B and Q move as E and F), said to be a win for White.
   In Dunsany's C (and the variant array Pawn Shop), the side with pieces tries to capture all 32 enemy pawns; the pawns try to mate as usual. In Sixteen Pawns, White removes her queen and places eight extra pawns on her third and fourth ranks (common configurations are a-h3, a-h4, bcfg/3/4, and bcfg3/cdef4). A variant allows White to remove a rook and place three or four pawns instead (in any of these games, the number of pawns can be increased or decreased for a handicap game).
   The Peasants' Revolt pits four black knights (with an optional pawn) against eight White pawns. Black should win, even without the pawn. A distant relative of this is Weak! (Black pawns can promote only to knights).
   The Maharajah and the Sepoys is a well-known game in which a normal army of White units (the Sepoys) face a single black king (the Maharajah), which moves and captures as an amazon. Black places the Maharajah on any vacant unattacked square, then White plays first. The object for both sides is checkmate. White's pawns do not promote. White has an easy win by gradually advancing forward, without leaving any units unguarded, being careful not to stalemate once the Maharajah is confined to its first rank. A simple "steamroller" strategy is a3/c3/b3/d3/Qc2/h3/e3/Ne2/g3*/f3*/Kf2*/Nd2/Bb2/Bg2/Ra2/Rh2, moving the sepoy army forward one rank without leaving any units unprotected (* moves may need to played in different order depending on the position of the Maharajah). A second advance restores the normal backrank order (a4/c4/b4/Qc3/d4/e4/f4/Bf3/h4/g4/etc.). Alister McIntyre in NA300 suggests that Black be given two amazons (one royal, one not) to balance the game. At some point Black may be able to sacrifice his 'queen' to open up the position, allowing his 'king' to penetrate and checkmate. Another possibility is using Shatranj moves for White's queen and bishops. Verney also mentions a game where White has two rows of pawns on her second and third ranks, with no pieces; the game is played as Dunsany's C. White should win.   
   In Deal C, each player receives a king, and 8 units determined by die roll (1/2 = P, 3/4/5/6 = Q/B/N/R), which are placed as desired (the king must not be placed in check) on their first two ranks (see Co3).
   Betza's Unequal Armies consists of about a dozen sets of alternate pieces (replacements for KQBNR) which make up armies roughly equal in strength to the orthodox army. These alternate armies can be matched against either the standard army or each other. In Chess A vs. Chess B, the players play under different rules (e.g. White moves as in U-Chess, Black as in Grid C). See also Cs4.

Cb -- Variable initial position
  Cb1 -- Free or random selection of array
   The best known game using variable arrays is Battle C. A screen is placed between the fourth and fifth ranks. Each player arranges her units on her first three (optionally: four) ranks in any desired formation, placing bishops on opposite colors, no pawns on the first rank, and only one pawn per file (the last rule can optionally be ignored). The screen is then removed and play proceeds as normal. A variant, Multimove Battle C, allows each player to secretly make a fixed number of moves (10 is suggested) from the standard array, no unit moving past the 3rd rank (cf. Shatranj (Cc1)). Play then proceeds as in Battle C. In Viennese Kriegspiel (a misnomer; it is not related to Kriegspiel [333]),  the kings are placed on first or second rank squares independently drawn by lot. These locations are then revealed to both players, who then secretly arrange the rest of their units in their own halves of the board (anywhere on their first four ranks without restrictions). Instant C is another relative of Battle C in which players secretly place their units anywhere on the entire board. When opposing units occupy the same square, the lower-ranking unit is removed (P (low),N,B,R,Q,K (high)). If equal, both are removed (if both kings occupy the same or adjacent squares, choose new arrangements). White than begins normally. Note: all of the above secret deployment games (as well as Baseline C below) can be played postally by sending initial arrangements to a disinterested third party, who will (after receiving both) relay each array to the opposing player, after which the game begins normally.
   Pre-Chess begins with each player having eight pawns on the second rank as normal; the first rank is empty. White and Black in turn place one piece at a time on vacant first-rank squares. No unit may be moved until each player has placed all eight pieces, after which play begins as normal. Bishops must be placed on opposite-colored squares. Symmetry is not required. Castling is permitted for king and rook starting in their standard locations. This is the best-known of a family of variants in which the first-rank pieces are rearranged, popular with orthodox players wishing to avoid 'book' openings. The unrestricted form of Pre-Chess is called Free Placement C (castling is abolished; bishops may be placed at will). Other forms are Real C, which differs in allowing castling (under normal restrictions) between a king and rook at any distance -- the king moves adjacent to the rook (if not adjacent already), and the rook hops to the other side of the king; Kaiser's Pre-Chess (K must be placed first, followed by Q/R/R/B/B/N/N; White places her king, then each player alternately places two at a time); Super Pre-Chess (a proposed version allowing players to select one of several optional pawn formations, as in Burmese C), and Baseline C (back-rank arrangements are made secretly, as in Battle C).
   Symmetric Pre-Chess uses a modified procedure to produce an array in which the White and Black armies are mirror images of each other. White places a piece on any desired first-rank square, Black places the same species of piece on the same file, then places another piece on a vacant square. White mirrors this placement and places a third piece, etc. Randomized C begins with each player having a randomly arranged back rank (one way is to shuffle a pile of eight playing cards (KQJJTT99, J/T/9 = R/B/N) and arrange the back rank pieces in the resulting order). Another way is for each player to alternately conceal a piece behind her back, placing it on a square pointed to by her opponent.
   Randomized Progressive C and Hopscotch C combine randomized back ranks with Scottish C and Marseillais C respectively (Hopscotch C forbids giving check on the first of two moves unless mate, and also bars castling). Parr has run some games in his postal games magazine Hopscotch, assigning back ranks to players himself. Lawrence has for a decade run a successful postal organization devoted to his variant Transcendental C -- this consists of two game matches (players play White in one game and Black in the other) in a form of randomized chess in which the players are assigned different random back ranks, generated by computer. Players may, on their first move only, transpose any two pieces on their back rank instead of moving a unit. There is another version called Auction TC, in which players bid tempi for the right to play White or Black.
   Pre-Chess variants may be combined in any desired way. In most variants, the recommended rule is that bishops must be placed on squares of opposite colors (in random variants, when bishops fall on squares of the same color, White exchanges his rightmost bishop with the piece to its left, Black matching this). There seems no reason to allow castling (except in randomized variants), as the placement should carry out the aims of castling. In symmetric variants, if desired, diagonal symmetry (king on same file as enemy queen and vice versa, so each player's pieces are in the same order left-to-right) can be used instead of mirror symmetry (kings on the same file).
   If bishops are required to be on squares of opposite colors, there are 4,147,200 possible arrays, ignoring reflections (1440 of these are symmetric). If there are no restrictions on bishops, there are 2520 symmetric and 12,700,800 total arrays. If diagonal symmetry is chosen, there are the same number of symmetric arrangements.
   In another variant of Pre-Chess, the kings are placed opposite each other on a file chosen by lot; other pieces are placed as in Pre-Chess. In yet another version, Black chooses the order of his back rank, White mirrors it and them makes his first move. In Griffith's C, White makes his normal first move, then Black may rearrange the White knights and bishops on the squares b1/c1/f1/g1 (bishops must be on opposite colors; if White moved a knight, it stays where it is) -- see changgi (Cc4); the game then proceeds as normal. In 1926, John C. Warblis proposed that each year a new arrangement of the back ranks be used in tournaments (see CA, A26). In Permutation C, White and Black agree on one of the 24 doubly symmetric arrangements (queen mirrors king), e.g. NQRBBRKN.
   Toroidal Pre-Chess is a variant for the 8x8 toroidal board (see Cj1). White and Black alternately place units on their first four ranks (pawns only on the first three). Kings cannot be left in check, so it is necessary to make a safe haven for the king (since a king in the open can be checked by an enemy bishop on two lines, impossible to block simultaneously). Pawns promote on the 8th rank; see Index for details.
   In Phantom C (1910), players alternate placing units on any vacant squares; play begins after all 32 units are placed. It is suggested that checks not be permitted until the 6th move. In Pawn Placement C, each player alternately places his king at will on his 1st rank, three pawns one-by-one on his 2nd/3rd/4th ranks, then play begins as normal. (Parton recommends placing a knight, then a bishop, after K/P/P/P). In Dutchess, each player removes up to 6 pieces from his starting array, both players removing the same combination of pieces.

  Cb2 -- Delayed deployment (see also Cv1)
   Pocket Knight C is a popular variant (even among orthodox players who normally avoid variants). Each player has a third knight (not placed initially) called the pocket knight in addition to the two on the board.  This knight can be placed on any vacant square on the board on any turn (variant: a knight cannot be dropped to give check) in place of a normal move (as in Chessgi -- see Cv1). In another form, one (or both) of the two knights (usually the queen knight) is removed to serve as the pocket knight. Kleptomaniac C is a more general variant in which some other piece is removed and becomes a 'pocket' piece.    In Free Opening C, the king and pawns are placed in their normal positions. Each player places two pieces anywhere on her first rank. Then each player makes a move. Before each succeeding move, a player may place one or two more additional pieces, which can be played immediately. He must place at least one piece before every other move, so all pieces must be in play before the 11th move is played. In Chess With Reserves, play begins with the the king and pawns in place. On each turn a player may place a piece (QRRBBNN) on any vacant first rank square or move a unit. In Placement C, kings are placed first (on their 1st or 2nd ranks), then players on each turn may either place another unit or move a unit, as desired (a rule forbidding checks before the 6th move is recommended). Some restrictions on placement may be needed (especially regarding pawns) to make this variant playable.
   In Lazy King C, kings are absent from the array. After Black's 12th move, White places his king on a vacant unchecked square, then Black does the same (compare Kaissa (Cc5)). Kings cannot move thereafter unless in check. The game suffers somewhat from drawish endgames.
   A more complex game is Deployment C, winner of a CV design contest in The Gamer. The board begins empty except for 'creation points', markers indicating where units may be placed, on each square of the first three ranks of each player. These are destroyed by moving across or landing on them.  See also All-Connect C (Co2), Jet C (Cp1).

  Cb3 -- Unidentified units
   In Chess in Disguise, each player has eight pawns and king placed normally, and seven pieces (QXCRNBB) placed secretly on her first rank (bishops on opposite colors);  checkers may be used in place of unidentified pieces. A piece must be identified when it gives check or is captured, otherwise the opponent must deduce its identity.    In Identific C, each player has the normal eight pieces plus four pawns. These are placed secretly anywhere in a player's own half of the board, again marked with checkers. Each unit must be identified on its first move by a characteristic move (which cannot be a capture): A move one square straight forward for a pawn, one square in any other direction for the king (which must be one of the first six units moved), two or more diagonally/orthogonally for a bishop/rook, a knight's move for a knight. The queen must be identified last, and can make any legal move. Play proceeds normally after all units are identified.

  Cb4 -- Creation and non-capture removal of units during play
   In Twinkle C, after each move, the moving player either removes a pawn of either color from the board, or adds a pawn of either color to any vacant square between the 2nd and 7th ranks. A pawn entered on its 2nd rank can doublestep (there is no e.p.). No more than eight pawns of each color can be in play at one time. A variation of this game is Four Seasons C, which alternates three-move phases of Blizzard (addition of a pawn), Avalanche C (see Cr1), Buzzard (removal of a pawn), and Twinkle C (addition or removal). The eight-pawn limit is not in effect. Blizzard and Buzzard do not work well on their own, resulting in either a board clogged with pawns or a pawnless game.
   In Kidnapping C, each player removes from the board one of their knights (if any remain) after Black's sixth move.  After Black's 12th/18th/24th, each player similarly removes a B/R/Q. No removal may place either king in check.

  Cb5 -- Variable units
   In Ambition C, each player after each move (except a move which removes an enemy check) demotes or promotes a unit of either color (except a king) one step up or down the usual scale (P-N-B-R-Q). The promotion/demotion cannot reverse that made by the opponent on his previous half-move. Ishkanian and Cohen found 1628 foolsmates with White mating on her second move; e.g. 1 c4(c4N) c5(c8R) 2 Nd6(e7N)#.
   Cubic C [166] uses cubical blocks (a king plus 9 pawns, each marked with the normal symbols for P/N/B/R). These can be turned to any value in place of a move, but there is a limit on the total value of an army.   Full rules are in VC2.
   Gryphon C is a complex game in which every unit promotes one step after each time it moves, eventually becoming a king. The object is to mate any king (as in Cx4).
   Turning Cube C is a complex variant in which each piece is a cube marked on each of its six sides with one or more arrows indicating the directions in which the piece can make its usual moves. The cubes are rolled at the start to produce armies of random ability; the position of a unit's arrows can be rotated after each move it makes (see [466,590]).
   In Genie C, each player has, in addition to her normal forces, a genie which can be placed on the board at any time. This piece has the power to make only four moves during a game; one each as a knight, bishop, rook, and queen in any order.

  Cb6 -- Choice of forces
   Free Choice C, described in WGR6, is a complex variant in which players select their own armies from a list of units, then place them in a 10x3 staging area, from which they are moved into the main 10x10 area of the board. In Generalized C, players use a similar selection system (from a list of over 100 pieces, with numerical values!), then place their units behind a row of pawns as in Pre-Chess on an agreed board (usually 8x8 or 10x10).

Cc -- Historical and regional games
  Cc1 -- the Shatranj family
   Chaturanga is the oldest known form of chess, developing in India sometime in the first millenium A.D. It was played on an 8x8 board with king, knight, rook, and pawns having their modern moves (but there was no castling and pawns could not doublestep). The king could make one knight move per game until checked. The fers and elephant were the forerunner of the modern queen and bishop. Robado is a draw; a stalemated player wins. Chaturaja is now believed to be an early offshoot of Chaturanga; it is the oldest form of four-handed chess (see Cy2) and the oldest form with dice (see Co3). A form of four- handed chess played in mediaeval Spain is [4]. When Chaturanga migrated to Persia it became Chatrang.    Shatranj, the Arabic modification of Chaturanga, reigned as the dominant form of chess for perhaps a thousand years. It was the first form of chess to be studied intensively (see Murray). It spread to Europe, where it was played throughout the Middle Ages as Mediaeval C, undergoing various modifications (most importantly the introduction of the modern queen and bishop), eventually becoming the chess of today. In Shatranj, kings are placed on the same files (not crosswise as in Chaturanga), and are allowed to make one knight's move per game. The fers can move as an elephant on its first move. A lone king loses (robado) unless it can bare the enemy king on its next move. The game usually begins with an opening stage in which both players make 10 or 12 moves at once, not crossing the centerline. One of these opening patterns (Mujannah) is given as the starting array for Middle Ages C, recommended for giving the modern player a feeling for how Shatranj was really played.
   Oblong C is a variation of Shatranj played on a 4x16 board. At least seven different arrays are known. It could be played with or without dice; Dekle has suggested playing it with modern moves. Short Assize C was a Shatranj variant in which the fers started the game sharing the e3/e6 square with a pawn (see Double Queen C, Ca1). See also Byzantine C and Citadel Zatrikion (Cj2). Minor variants of Shatranj include [11, 353, and 413].  Dekle has speculated on what the original form of chess may have been like; his game Protochess uses non-leaping elephant, dabbabba, and knight, a royal wazir as king, and non-royal wazirs as pawns (non- promoting, capturing as they move). The object is capture of the king or robado.

  Cc2 -- Regional great chesses
   A number of variants played on large boards were devised in Europe and Asia (especially Turkey) during the late Middle Ages and the Renaissance. A few of these were Shatranj variants, but most used the modern pieces, often adding the amazon, chancellor, and/or cardinal (see Cf1). The decimal variant Qatranj added a piece which moved as a king, but only in the direction of the opposing king. The most popular of these great chesses was Tamerlane's C, played on an 11x10 board with two citadels, left of a9 and right of k2 (another game with citadels was Shatranj al-Husun). Tamerlane's C used 10 different pieces, and had complex rules which even allowed for a lost king to be replaced by promotion of certain pawns. Grande Acedrex is a 12x12 variant played in mediaeval Spain, with a number of complicated new pieces. It sometimes was played with an eight-sided die. Other great chesses include [435, 485, 497, 531, 549, 550, and 638]. The descriptions of many of these chesses vary widely from source to source.
   The most popular form of chess in Europe between Shatranj and modern chess was Courier C. The Courier was equivalent to the modern bishop (Courier players thought it stronger than the rook!), and may have helped bring about the modern game. The game usually began with a stylized opening, White playing a4, l4, g4, and Fg3, and Black moves a5, l5, g5, and Fg6. The pawn promotion rule is not known; the simplest way to play is to allow promotion to fers as in Shatranj.  Another possibility is a complex rule found in a form of chess played in the German village of Strobeck.

  Cc3 -- the Shogi family
   Shogi, the Japanese version of chess, is played on a 9x9 board. There are a number of historical variants of shogi, ranging in size from Tori Shogi to the monstrous Tai Shogi. The pieces and moves for these games are beyond the scope of this issue (contact George Hodges for more information). Shogi's most notable characteristic is its re-entry of captured units via drops (believed to have been introduced in the late 16th century along with the standard 9x9 game). Drops are also used in Tori Shogi, but not in Chu Shogi and the larger variants. They may be optionally used in Wa Shogi; Schmittberger prefers the game with drops, Hodges without. In shogi and its variants, most units are initially weak, but promote to more powerful units. Piece names are generally consistent between games; all of the pieces in Chu Shogi, for example, appear in Dai Shogi. The 25x25 variant Tai Shogi, played with 177 pieces per side, is almost certainly the largest CV ever created.
   The rules for shogi are too involved to describe here (the older books by Ohara and Leggett do not even have complete rules) -- the reader is referred to Fairbairn's book for up-to-date rules, as well as strategy. Hodges sells rule pamphlets for the other shogi variants. The Index gives (where available to me) the board sizes, number of units per side, and number of different species (including promoted ones) for these games (in order of size): 621, 552, 668, 128, 277, 172, 610, 171, 367, 598. Other variants of shogi are known. In Queen Shogi, each player has an orthodox queen (which does not promote) at the center of the second rank (e2/e8). Dekle has devised hexagonal, three-dimensional, spherical, and triangular variants of shogi [284, 572, 575, 637]. See also An-nan C (Cq1), originally a shogi variant. See Cv1 for chessgi and other Western variants using drops as in shogi.

  Cc4 -- Other Asian chesses
    The Index cites a number of books and magazine articles on xiang qi; I therefore refrain from giving the rules here. Another good source is said to be books in Chinese, which usually contain many game transcripts. One can learn to read these with a bit of effort (see the explanation in NA181). San-Kwo-Chi is a three-handed variant (see Cy1) of xiang qi, each side having one extra piece which moves as a non-leaping camel ((1,1)/(2,0)).  Wurman  describes several other variants, including the only CV I have seen designed for seven players.  There is also an 11x11 version of xiang qi without a river.
   Changgi, the Korean version of chess, is a close relative of xiang qi (and can be played with the same equipment if desired), but there are a number of differences in the rules. Wurman is the most reliable source. AHC and CVARM have minor omissions: The rook, cannon, and pawn as well as the king and guards can move along the diagonals of the palace (the cannon leaping from one corner to the diagonally opposite one, over an occupied central square; the pawn going diagonally forward only). Both players may reverse the positions of knight and elephant on either or both sides of the board if desired, but each player must have one knight and one elephant on each side of his array.
   Burmese C is a very old regional game in which players have great freedom in the initial placement of their pieces. There are two optional pawn formations, and pieces may be placed anywhere on or behind the pawn line. A related game with a fixed array is Makrook, the Thai version of chess; both games use the same pieces, including the silver general from shogi. In Makrook, pawns promote to fers on the sixth rank (this also resembles shogi), and king and fers may optionally move, as knight and elephant respectively, on their first move. Several other regional chesses (see AHC) are minor variants of the international game (Chator -- the Malay variety, Hindustani C, and Parsi C).

  Cc5 -- Literary chesses
   Jetan is a decimal form of chess played on Mars in Burroughs' science fiction novel The Chessmen of Mars. The main goal is to capture the enemy princess, which can move three squares in any combination of directions.

   Kaissa, another decimal game, appears in John Norman's novel The Players of Gor.  It is characterized by several limited-range pieces; the goal is to capture the enemy 'home stone', a non-capturing king which is placed on the first rank between moves 8 and 10 (see Cb2).  Kaissa was reviewed in WGR 3, page 17.  John Norman's novel Players of Gor was published about 5 years later than the commercial version of Kaissa (according to the game's copyright date).  The commercial version may have been based on accounts of Kaissa from earlier novels in the series.   There is an account of a Kaissa game starting on page 230 of Players of Gor, ending in a neat forced mate.   But this game does not follow the same rules as the commercial version: according to the book, spearman are allowed to promote, and may move sideways or diagonally forward as well as straight forward; also, the scribe and ubara are not limited in range.


Cd -- Modified pawns and promotion
  Cd1 -- Modified pawns
   Several different varieties of pawn have been devised, and can be used in place of standard pawns in variants. Unless specified, en passant is extended in all of the games below (a pawn which moves two or more squares, crossing a square attacked by an enemy pawn, may be captured en passant). The most popular modified pawn is found in Berolina C. The Berolina pawn moves one square diagonally forward (with the option of two on its first move), and captures one square straight forward, the reverse of orthochess (an example of en passant is d2b4, c4xc3 e.p.). A foolsmate is 1 g2e4 e7c5 2 f2d4 Qh4+ 3 h2g3 Qxg3#. An alternate array for Berolina C (with no doublestep) is Corner C.   Soldier C uses the Oriental pawn (as found in shogi or xiang qi), which has no doublestep option and captures as it moves -- one square straight ahead. The 'pawn' in Arrow Pawn C can move (regardless of location) one or two squares in any orthogonal direction and capture one square diagonally in any direction. It does not promote. A similar pawn (but without doublestep power) appeared in 1770 in The Game of War, an 11x11 variant with orthodox pieces, and 'fusiliers' which move as wazirs, and capture as ferses -- they also do not promote.
   In Fish C, pawns (called fish) can move (but not capture) one square straight backwards in addition to their normal power. They may move back to the 1st rank, and may doublestep from the first or second rank. In Taxi Pawn C, pawns may move up to three squares forward from the second rank on their first move. Thereafter they may move one square straight forward or backward when not capturing, but may not retreat to their first rank. They do not have the doublestep or triplestep option if they return to their second rank. Promotion on the eighth rank is optional. initial or one square backward from any rank.
   In Superpawn C, the king and queen (d and e) pawns can move and capture up to three squares forward or one square sideways (different Super Pawns are used in Chess II and Super C). In P-Chess, pawns are orthodox with the added ability to move one square forward diagonally even when not capturing. In Magic C, the pawns have expanded powers, adding the two forwardmost knight moves to their capturing power and the other two forward knight moves to their movement power. E.g., a white pawn at d5 can move to b6 and f6 in addition to d6, and can capture on c7 and e7 as well as c6 and e6. A pawn on its second rank can doublestep as normal (not leaping); e.p. applies only to the orthodox doublestep. [This could also be classified under Cf1].  See also Kinglet C (Cx3), Chess II (Cf1).

  Cd2 -- Modified promotion
   Mecklenbeck C modifies not the pawn's move, but its promotion.  Mecklenbeck pawns may promote on the sixth or seventh rank if desired, (see Makrook (Cc4)). They must promote if they reach the eighth rank (similar pawns, promoting on the 8th/9th/10th rank, are used in the decimal variant Grand C). The Mecklenbeck pawn was invented to allow problems involving triple check with en passant capture (Black Kd6, Pe7; White Rd3, Bf2, Pd5 : 1 Bg3+ e5 2 de6=Q(e.p.)+++). Mecklenbeck is perhaps too dry a game for most CV enthusiasts; many games end without early promotion coming into play. Mecklenbeck might be more interesting combined with another variant such as progressive (or perhaps Avalanche?!).
   Chess to Go was an impromptu invention at NV'88. It is played on a 12x12 board (the first game was played on a 13-line go board), with the units arranged normally in the central 8x8 (c3 to j10). Units move as normal (the extra space gives much more freedom of movement than games such as Howell C (Ch1) or Corridor C (Ca1)). A pawn may promote to knight or bishop on reaching the eighth rank (i.e., 6th from the rank where the pieces begin), or may remain a pawn and promote to R/B/N on the ninth rank or Q/R/B/N on the tenth (opponent's piece rank).
   In Fast Track C, pawns may promote to N on their 5th rank, N/B on their 6th, N/B/R on their 7th, or N/B/R/Q on their 8th (mandatory if not already promoted). A variant of this also allows pawns to move one square sideways (as in changgi); they can only promote by a sideways move (promotion on the 8th becomes optional). In Progression C, pawns do not promote in the usual sense, but pawns when on their 5th/6th/7th/8th ranks move as N/B/R/Q respectively.
   In Fiverider C, pawns can promote only to one of the five simplest riders: rook, bishop, nightrider, camelrider (moves from a8 to b5, c2, d7, or g6), or zebrarider (moves from h8 to e6, b4, f5, or d2). A recent commercial decimal CV, Modern American C, allows certain pawns to promote to two pieces, but the rules are not clear on how this takes place. See also Hydra C, a multiple target variant (Cx3), and One-Shot C (Co1). See Cb5 for variants in which units other than pawns can promote (also the case in shogi (Cc3) and Leaper Chessgi (Cg5)).

Ce -- Modified kings (see also Cx3,Cx4)
   In Knightmate, the king is replaced by a royal knight at e1/e8.  Knights castle as orthochess kings. They may leap attacked squares, even when castling. Both orthodox knights are replaced by non-royal kings. Pawns may promote to non-royal king, but not to knight.  The object is to checkmate the opposing knight.  A more complex decimal version (without kings) is Centaur Royal, in which the object is to capture the enemy knight (HSCD has an alternate array with two CR's per side; the object is to capture both -- or the CR's on a9/h2 can be omitted if desired). A queen can mate a lone knight without any help, using a series of checks from two squares away diagonally, or 1 or 3 squares away orthogonally (with WQa1 and BNd5, White mates by 1 Qd4+ Ne7 2 Qe4+ Nc8 3 Qe6+ Na7 4 Qa6#).
   In Rettah C, kings (called Rettahs) have the move of amazons (queen plus knight). The object is to capture the opposing Rettah, except in Double Rettah (see Cx4). In variants with two Rettahs per side, the object is to capture both enemy Rettahs (as in Cx3), and a player who has lost one Rettah may promote a pawn reaching the last rank to a second Rettah. When a Rettah is attacked, the attacking unit (one of them in the case of double check) must be captured by the Rettah or another friendly unit. If no other unit can do so, one of the Rettahs must capture, even if it puts itself en prise (losing the game if it is the only friendly Rettah remaining). Several variants were described by Parton in various publications (including an optional rule in NJENO allowing pawns to move as in P-Chess, enabling them to be doubled for defense). In Decimal Rettah, a unit attacking a Rettah must be captured by a Rettah (this rule was eliminated in later versions). A variant of Decimal Rettah is Absolute Rettah, in which any unit can attack a Rettah (and must be captured by a Rettah), but a Rettah can actually be captured only by an opposing Rettah -- a goal is therefore to attack an enemy Rettah with a unit guarded by one of your own Rettahs. Giveaway Rettah can be played with any of the arrays listed in the Index [183, 208, 516].
   In Emperor King C, the kings are emperors --they can move to any vacant square or capture any unguarded enemy unit, including the enemy emperor -- emperors must therefore always be guarded. The object is to capture or checkmate the enemy emperor, by capturing all of the units except the enemy emperor, or attacking every square from which it can be guarded (e.g., the Black emperor is mated in the position 8/ppp5/1k5R/32/7K).    In Letzen C, kings move and capture as queens, but cannot cross squares attacked by unpinned enemy units except when capturing units attacking them. Another version of this is Liberation C, in which the queen is royal and the king is non-royal (see also 2000 A.D.). Pawns may promote to a Fischer, a piece which can leap to any square within four squares distance.
   In Permuting C, each king may switch places (in place of a regular move) four times a game: once each with a friendly N/B/R/Q in that order.  If all pieces of a given species are lost, its 'turn' is skipped. A king may escape check by a switching move. See also Neutral King C (Cr2).

Cf -- Combined pieces
  Cf1 -- Pieces with added knight power
   Dozens of variations have been introduced using pieces with knight power added to their normal power, most often the amazon (Q+N), cardinal (B+N), and chancellor (R+N). Arrays for most of these games are found in the Index. Obviously mating with king and chancellor (or amazon) against a lone king is easy; king and cardinal can mate a lone king with a bit more effort (e.g., WCa1, WKh1, BKd5; White mates by 1 Kg2 Ke4 2 Cc3+ Kf5 3 Kf3 Ke6  4 Ke4 Kd6  5 Cb4+ Ke6  6 Cc5+ Kf6  7 Kf4 Kg6  8 Ce6 Kf6 9 Cd5+ Kg6  10 Kg4 Kg7  11 Kg5 Kf8 (11...Kh7?? 12 Cf6#) 12 Kf6 Ke8 13 Cc6+ Kf8 14 Cd7+ Kg8 15 Kg6 Kh8 16 Cf6#).
   Amazon C, in which the queen is replaced with an amazon, was proposed in 1891, but said by Capablanca to be too drawish. Angel C calls the queen-plus-knight an Angel, adding it to the right of the king on a 9x8 board (the placing of bishops on the same color -- opposite that of the opponent's -- is intentional). Draws are minimized by a rule forbidding a player to capture his opponent's Angel if his own could be captured on the next half-move (if your Angel is attacked, you may protect it by attacking your opponent's). A foolsmate is 1 e4 Ac6 2 Qe2 Axc2#). Other games using the Amazon include Amazon Queen, Century C, and Wyvern C (see also Cc2).
   Chancellor C similarly adds a chancellor to the right of the king on a 9x9 board. A simpler proposal is Almost Chess, in which the chancellor replaces the queen in the orthodox game (a foolsmate is 1 Qc3 Nf6 2 Qxc7#). In Riviere's C, chancellors replace both rooks; also in the complex 9x9 variant Kristensen's C. The mating power of the chancellor is shown in a problem by A. H. Robbins from Foster's Chancellor Chess: 24/2P5/3P4/3kN3/2X5/4K3; White mates in 3 by 1 Xc4 Ke4 2 Nd5, with four mates following depending on Black's second move (e.g. 2...Kd5 3 Xd6#).
   In Queenless C, the queen is replaced by a cardinal (analogous to Amazon C/Almost C); in Modern C, the cardinal is added to a 9x9 board (analogous to Angel C/Chancellor C). Modern C has the flaw of having all bishops on dark squares.  Other games using the cardinal include the minichess Lilliputian C and the Emperor's Game (with the amazon also).
   A large group of variants add both chancellor and cardinal to the normal forces on either a 10x8 or 10x10 board; these include Bird's C,  Capablanca's C (2 versions), Carrera's C, and Grand C. One exception is Legler's C, a clever variant which replaces one knight with a cardinal and one rook with a chancellor. This allows players to experience the chancellor and cardinal on the orthodox 8x8 board (one rook can be inverted to signify a chancellor, and one knight somehow marked to signify the cardinal). Wolf C is an 8x10 variant which also includes the nightrider and other pieces (see also Dekle's Nightrider C (Cg2) and Airplane C (Cg5)).
   Among games with all three pieces are: Quatrochess (see Cy2), The Sultan's Game, Supercapablanca C, and Valentine's C. In Chess II, there are also zebras with added knight power ('super knights'). Pawns which begin on their third rank have E5 movement. Pawns beginning on their second rank are 'super pawns', able to move one or two squares straight forward (E6) and capture one or two squares diagonally forward at any time. Pawns cannot jump; en passant applies to all multistep moves. The 'super pawn' in Super C is similar, except that it can jump, but cannot doublestep after its initial move except when capturing.
   Cavalry C gives added knight power to every unit (pawns add the 4 forward knight moves only -- see Magic C (Cd1)). The king in addition can move as a non-leaping elephant or dabbaba; two kings can be two squares apart (orthogonally or diagonally) only if there is an intervening unit. The knights have the added power of camel plus zebra; i.e., they can reach every square within three squares except those reachable by an orthodox queen. Maus's 1923 pamphlet gives some sample mates (8/3N1k2/5B2/8/4K3/24; white mates in two by 1 Ng6 Kh6 2 Ne5#).
   See also Wildebeest C (Cg1) for a combined camel-knight.

  Cf2 -- Pieces with different capturing moves
   In orthodox chess, the pawn has a capturing move different from its non-capturing move. Several variants with pieces of this type have been proposed. In Semi-Queen C, two new pieces are added. The roshop moves as a rook but captures as a bishop, while the biok moves as a bishop and captures as a rook. Thinktank C has all six combinations of rook/knight/ bishop. In Sniper C, the Q/N/R/B exchange moving/capturing powers as in Frontier C (see Cl2).

Cg -- Other new pieces
  Cg1 -- New leapers
   Arch C adds to the modern pieces the fers and the squirrel, which leaps to any square two squares away (knight + elephant + dabbaba). The squirrel is also used in Nine File C, and combines with the rook in Double-King C (Cx3). Mexican C, published here for the first time, is a decimal variant in which each side has two camels,  here called 'conquistadors'. Wildebeest C adds two camels and a wildebeest (gnu) (combining camel and knight -- about a pawn stronger than a rook, but slightly weaker than a squirrel) on an 11x10 board (see the note in Game News). A centrally placed wildebeest can reach any square on an 8x8 board in one or two moves, except the four squares (0,3) away!
   In Dabbabante C, the dabbabante can leap to any square of the same color along rook lines, passing over any number of vacant and occupied squares. It captures by replacement. Pinsard's C is a decimal variant with two new pieces combining elephant and dabbabba. The archer in the minichess Archer C (Ch2) combines the power of elephant plus wazir (this is about as strong as a camel, but two archers can force mate). The rook in Archer C is hobbled -- it cannot move to adjacent squares (see Co2).

  Cg2 -- New riders
   The second most popular fairy chess piece used in problems (behind the grasshopper) is the nightrider. These may simply be used to replace knights in the orthodox game. Nightrider C is a variant designed so that the nightrider is the most powerful piece on the board (each side removes both knights and replaces the queen with a nightrider). Dekle has proposed a version using a very powerful set of pieces (as in Cf1).
   In Ninerider C, the knight becomes a nightrider, the rook adds dabbaba-rider power to its normal wazir-rider power, the bishop adds alfil-rider to its ferz-rider power, and the queen combines (3,0)-, (3,1)-, (3,2)-, and (3,3)-riders. Kings and pawns are normal. A variant makes the queen less overpowering by instead giving the (3,0)-rider power to the rook and the (3,3)-rider power to the bishop. The array must be crosswise to prevent 1 Rxh7 Rxh7 2 Qxh7# (via f4). See also Five-Rider C (Cd2).
   Falcon-Hunter C uses two new pieces with Y-shaped moves (see the move descriptions in the Additional Pieces section).  In one version (Hunter C), falcons replace both bishops and hunters both rooks. The queen can castle on either side of the board (O-O-Q = Qb1/Ra1c1, O-O-O-Q = Qf1/Rh1e1) to make hunters easier to develop; both king and queen may castle with their near rooks in the same game. There is also a decimal version in which the new pieces are added to the array. A third version allows one falcon and one hunter to be entered on vacant first-rank squares (in place of a move) to replace lost pieces. Anytime after a player loses one piece, she may place the falcon or hunter. Anytime after a second piece is lost, she may place the other.
   Dekle has suggested a modified queen called a duchess (combining falcon and hunter, it moves as a queen in any direction except orthogonally sideways). He uses it in his games Falcon-Hunter Chessgi (Hu/Fa/Du/P promote to R/H/Q/V) and Lion C. The latter game also uses the Lion from Chu Shogi, a piece which makes one or two king moves per turn, capturing on either or both moves if desired. It can also return to its starting square or leap as a squirrel without affecting units it jumps over.
   In Archbishop C, the archbishop (symbolized A in the Index array) must make one right-angle turn during its move (as if hitting an invisible wall in Billiards C); it may stop or capture only after making its turn. In the minichess Warrior C (Ch2), the warrior is the piece we call here the spider -- note that it changes color on every move.

  Cg3 -- Hoppers
   In Columbia Cannon C, rooks, bishops, and queens make cannon moves (along their normal lines) whether capturing or not (as in changgi). Knights combine the power of wazir and dabbaba, leaping one or two squares orthogonally. Pawns and kings move and capture normally. Phil Cohen mistated the rules in NA210, accidentally creating Cohen's Error C (R/B/Q make cannon moves only when capturing, as in xiang qi).    The latter is similar to the simpler version of Leo C, in which the knight, pawn, and king move and capture normally, while the queen (called Leo), rook (Pao), and bishop (Vao) move normally but capture with cannon moves. The more complex version of Leo C replaces orthodox pawns with Berolina pawns, and the orthodox knight with the Mao (oriental knight from xiang qi and changgi), which does not leap -- it moves one square orthogonally followed by one square diagonally, with the same eight possible destinations as the orthodox knight, but an orthogonally adjacent unit blocks two moves (e.g. a Mao at c3 cannot move to d5 or b5 if c4 is occupied). In both versions of Leo C, pawns promote to orthodox Q/R/B/N, since cannon-movers are weaker in the endgame. CCC Chess allows units to move and capture as in either Columbia Cannon C or as in orthochess. See also Columbia Cannon Transchess (Cv2) (Columbia Cannon Conversion C is unplayable because of the 1/2 move 'foolsmate' 1 Qb3#).
   Decimal Oriental C is Parton's westernized version of changgi (the cannon must hop over a screen to move or capture). Grasshopper C adds a row of eight grasshoppers to each player's army. In Vault C, Q/R/B may hop, if desired, over friendly units when not capturing. In Screen C, Q/R/B may hop over friendly knights on a capturing or non-capturing move.

  Cg4 -- Chess/checkers combinations
   Several hybrid games combining chess and checkers have been devised. The most popular of these is Cheskers, played on the 32 black squares of the 8x8 board. Each army is composed of eight pawns (moving and capturing as checker men), two kings (as in checkers), one bishop (as in chess), and one cook (as the chess camel). Pawns promote on the 8th rank to cook, bishop, or king -- the object is to capture all of the enemy kings, including any promoted ones (compare Hydra C (Cx3)). A pawn making one or more captures must stop upon promotion. Captures are obligatory (unless the only captures available are by bishops and/or cooks), but the moving player has a free choice of which capture to make. A stalemated player loses. A simpler game, without checkers captures, is Chess Draughts. The kings and cook are absent, and one queen (as the chess fers) is added. Pawns move and capture diagonally forward and promote to bishops; the object is to capture the opponent's queen.
   Kiwi Checkers is a new checkers variant using some elements of CV's. It is not truly a CV, but I include it here to show how the distinction between CV's and non-chess games can be blurred. Checkers can be stacked up to three in a square (stacks of 2 or 3 can be created only by drops). Captured units are dissolved into single checkers and added to the captor's reserve, from which they can be reentered (1, 2, or 3 together) onto vacant or friendly-occupied squares as in shogi/chessgi.  A single checker ('kiwi') or double stack ('tui') moves as a checker; a triple stack ('moa') as a king. A kiwi or tui reaching its 8th rank is immobile until increased to a moa by dropping onto it. Captures are compulsory, and the capture taking the largest number of checkers must be chosen. The object is to deprive the opponent of moves by capturing or blocking all of his units and depleting his reserve.
   In Damate, all units move as in chess, but capture by leaping as in checkers. The king is a shortleaper. The pawn captures by shortleaping diagonally forward only [variant: the pawn can move or capture in three directions: straight or diagonally forward]. The queen is a longleaper, the bishop a diagonal longleaper, and the rook an orthogonal one. The knight lands in its normal squares, capturing adjacent units it passes over (Nc3 moves to d5 to capture c4 or d4; it can also go to b5 to capture c4). [Variant: the knight makes a double move in one direction, capturing a unit a knight's move away; i.e. Nc3 leaps to e7 to capture d5]. Pawns promote in the enemy half of the board to any piece, including king; promotion ends a series of captures. Captures are obligatory, and multiple captures are allowed (the largest number of enemy units must be taken); enemy units are left on the board until a series of captures is complete. The object is take-all; a player who cannot move loses by stalemate. The game may also be played as Giveaway. Either form can be played on an 8x8 board from the orthodox array, or on the 10x10 board [173]. Damatic C is the same game with the alternate objective of capturing the enemy king, and a choice of three decimal arrays. Dekle has invented a similar game called Checker-Chess.
   In Leapfrog C, all units move and capture as in checkers (in all eight directions), but give check as in chess. The object is checkmate. Jesskers (invented by a nine-year-old boy!) is a game of chess and checkers played on the same board with the normal arrays (chess and checker units may coexist on the same squares; both are captured together by an enemy chess unit entering the square or an enemy checker leaping over it). A player may move either a checker or a chess unit on his turn. The object is to capture the enemy king. In Longleaper C, the L moves as a queen and captures by longleap (multiple captures along one line are possible).

  Cg5 -- Miscellaneous pieces
   Several variants have been devised using different forms of airplanes -- pieces with the power to fly over units of either color. Atomic C is a complex and violent modern variant on a 12x12 board with tanks, airplanes, and atom bombs (full rules in JENO). In Airplane C, the airplane moves along queen lines, and can pass over any number of units of both colors, landing only in an empty square. It can capture one enemy unit per turn by landing in the empty square immediately beyond it. The standard game is played on a decimal board; a simple 8x8 version can be played by replacing knights with airplanes. In Aviation C, the knight pawns (b and g) are airplanes,  moving and capturing (by replacement) like bishops, but able to pass over any number of occupied squares. They capture only like pawns until they leave their initial squares.
   Ploy is a commercial CV in which each unit is marked with lines of attack in one to four directions. A piece may either move or turn ([590 and 640] also have directional pieces). Quantum C is a variant on a 6x8 board in which units (8 per side) move according to mathematical equations (a piece labeled y=x+1 can leap (0,1), (1,2), (2,3), etc. Leaper Chessgi is a shogi-like game in which all units except the king can promote on the 6th rank or beyond.

Ch -- Plane boards
  Ch1 -- Great chess (rectangular boards greater than 10x10)
   The family of games played on boards larger than 8x8 (especially larger than 10x10) is known as great chess (Paletta in Chess Spectrum Newsletter 2 calls it macrochess). Certainly the most popular board other than the orthodox 8x8 board is the 10x10 square board. There have been dozens of variants designed for this board; collectively these are referred to as decimal chess. Carrera's C (and its successors Bird's C and Capablanca's C) are played on 10x8 boards. Another important variant is the popular medieval game of Courier C, played on a 12x8 board, which may have been responsible for introducing the bishop into modern chess.  All of these large-board variants involve new pieces, and are covered in earlier sections.
   Robin King has pointed out a possible flaw in some 8x10 and 10x10 variants, in which pawns start on the second rank, are only allowed the usual initial doublestep, and bishops are placed at c1/c10 and f1/f10 (e.g.  Super C,  Bird's C, and Grand C).  The usually desirable doublesteps of the central e and f pawns actually hamper development -- instead of opening lines for the bishops, they actually block bishop lines (the array in Reversed Minor Pieces is undesirable for the same reason). It is perhaps preferable, then, to either allow pawns on the 10x10 board an initial triplestep (this also helps speed up the game), or to change the opening array to RN*BQKB*NR (* denotes the added pieces).  This may also be useful when playing any form of Pre-Chess (see Cb1).
   A few variants without new pieces have been played on rectangular (non-square) boards. Oblong C (a form of Shatranj (Cc1)) is played on a 4x16 board -- the same board has been used for a game using modern pieces. Howell's C is a 10x10 relative of Morley's and Mouterde's C.  See The Game of War (Cd1), an 11x11 variant with mainly orthodox pieces, and a later variant, The Prussian National Game (Cu2). See Cd2 for Chess to Go, a 12x12 variant with orthodox forces. Moeser devised games in which units may move on the corners (Schess) and edges (Simocochess) of squares (equivalent to play on a 17x17 board).

  Ch2 -- Minichess (smaller than 8x8)
   Another set of variants, referred to collectively as minichess, involve reduced forces on a small board, to produce a shorter and simpler game. (The smallest board which has been used in a CV is the 3x3 board used in the commercial CV Jet C, but this game is too complex to be classified along with the other minichesses.)  The earliest Western proposal for minichess is the 1930 variant Petty C, played on a 5x6 board with one of each piece plus five pawns (AISE plays a similar game on a 5x5 board). A famous minichess is Los Alamos C, played on a 6x6 board without bishops. This game was devised for use in an early chess-playing program, for which the standard game had too many combinations. A similar game was proposed later as one of a set of 6x6 variants under the name Wardley's C. This has four versions, depending on whether rooks, knights, bishops, or king and queen (?!) are eliminated. The last version is a bizarre game in which the first pawn on each side must promote to king, the object being to mate it.
   One minichess, Chi Chi's Chess, is played on a nearly full 4x8 board (the b/f/g pawns are removed for both sides). Pawns move one square straight forward or backward and capture one square diagonally in any direction (i.e. a white pawn can move like a black pawn and vice versa). White is not permitted to move a pawn on his first move. This game was popular in NOST for a time, but Paul Yearout and Wally Whiteman found that White should always win. [The main line is 1 Nxc3+ Qxc3 2 exd3+ Bxd3 3 Qf3+ Kd4 4 dxc3+ Kxc3 (4...Kc4 5 cxb4=Q+) 5 cxd3 Nxd3+ 6 Bxd3 etc. (2...Qxd3 3 cxd3+ Nxd3+ 4 Bxd3+ Kxd3 5 dxe3+ etc.)].
   Other variations listed in the index with complete descriptions of board size, array, and special rules: 42, 308, 349 (also Cf1), 382-384, and 558. See also Archer C (Cg1), Jet C (Cp1), and Warrior C (Cg2).

  Ch3 -- Irregular (non-rectangular) boards
   Fortress C, Morley's C, and Mouterde's C are described in the Index using - as a symbol for squares missing from a regular rectangular shape.  Chess Too, advertised in Chess Life but never sold, seems to be a form of Diamond C on an 8x9 board with two corners truncated. In Fortress C, the board is 3x8 + 4x4 + 3x8; a pawn blocked by a unit of either color can hop over it (two squares forward) to a vacant square. Cross C is an Australian commercial CV, played two-handed on a 4x4 board with four 3x4 wings. 
   Several  games have been played on boards containing holes.  Centerless C eliminates the de45 squares (which cannot be crossed, but knights can leap them), and the d and e pawns (see Quatrochess (Cy2)).  Lilac Tree C is a more general form in which an arbitrary 2x2 region is removed. This was proposed as a variant for a giant outdoor chess board in a yard with a tree. It sounds like a joke, but was actually tried in a NOST game.
  Ch4 -- Infinite boards
   Two mathematically oriented games, too complex to describe here, are Infinite Plane C, played on a board of squares infinite in all directions, and Dense C, played on a unit coordinate square, running from 0.0 to 1.0 in both directions (bounded but with an infinite number of board locations).

Ci -- Multidimensional boards
  Ci1 -- Three-dimensional boards
   In true three-dimensional chess, there are three main types of movement. The rook moves along any of three lines of orthogonally adjacent cells, passing through cube faces (e.g. from Aa1 to Aa8, Ah1, or Ha1). The bishop moves along any of six lines of cells diagonally adjacent within a single plane, passing through cube edges (e.g. from Ac1 to Ah6, Hc8, or Fh1). A third piece, called a unicorn, moves along any of four lines of cells connected diagonally in different planes, passing through cube corners (e.g. from Af1 to Fa6 or Ch3). Kings usually move to any of the 26 adjacent cells. Queens combine powers of rook, bishop, and unicorn. Sometimes the unicorn is eliminated; the bishop may combine bishop plus unicorn powers. Knights have their normal move in any of three planes; a knight away from the edge can thus reach twenty-four squares (from Cf3 : Ae3, Af2, Af4, Ag3 (and the same four on level E), Bd3, Bf1, Bf5, Bh3 (and the same four on level D), and the usual eight on level C). One feature of three-dimensional chess is that rooks are weaker than bishops. A lone king can be mated by a king and queen, king and two bishops, or king, bishop, and rook, but not king and two rooks.
   T. R. Dawson composed a simple but elegant problem in 1915 to show the move of the bishop in three-dimensional chess (p.34, Caissa's Fairy Tales): 5x5x5:25//19p5//18p6//9p3p1p4p4//15p4k1K1B//. White mates in two via B-Ce3, with four mating moves depending on which black pawn moves.
   In Godson's C, the most playable 8x8x8 variant, each side has an orthodox set of units plus eight extra pawns (White's pieces along A1 rank, pawns along A2 and B1 ranks; Black's pieces on H8, pawns along H7 and G8). The pieces move as described above. White pawns move one square toward rank 8 on the same level, or up one level. On their first move they may go up two levels, forward two levels, or up one and forward one. They capture one square diagonally like a bishop, not moving down or backward; a white pawn at Cf3 can capture on Ce4, Cg4, De3, Df4, or Dg3. Black pawns move down or towards rank 1 in the same way. There is no en passant; pawns reaching the opposing starting rank promote to whatever piece started there (to queen also at Ae1/He8).
   Kog C is played on an 8x8x8 board, with each side having a huge army of 64 units: 40 pawns, king and queen, and 22 other pieces (with names such as hippogriff and favourite) using 7 combinations of the standard rook, bishop, and unicorn (here called fool) moves. There is a combined bishop/unicorn called an archbishop.
   Raumschach is a 5x5x5 variant with standard piece movement. Tedco (full rules in NA90) and 3-Dimensional C [614] are commercial 4x4x4 variants, with orthodox 16-unit armies and simplified moves. Cubic C [165] is a 6x6x6 variant with standard piece moves. Pawns move and capture forward as kings, to any of nine squares. Parton also devised a version [601] using pieces from Tamerlane's C. The fers and elephant leap one and two squares respectively as bishops; the zurafa moves as the spider but cannot make a move equivalent to a knight's move.
   Stereo-Chess is a variant played on an 8x8 board with four additional 4x4 boards (designated ABCD) stacked above cf36. The array is orthodox on the 8x8 board. There is no unicorn; the queen (but not the bishop) includes unicorn power. Pawns move as usual on any level, and can also move straight up or down one level. They can capture upwards, going forward or sideways as bishops. Pawns promote on the last rank of any level (8th of bottom, 6th of ABCD for White, 1st/3rd for Black).
   Another group of variants are not fully three-dimensional, but consist of boards stacked one above the other. The most popular design is 3x8x8, three orthodox boards arranged vertically, with White's units arranged normally from Aa1 to Ah2, Black from Ca7 to Ch8. Each unit can make its normal move on the board it starts on, transferring to the same square on the next higher or lower board under specified rules which vary from version to version. Examples: [113, 315, 571]. Quadrivalent C is a complex 4x8x8 variant (full rules in JENO). Dekle has devised games for 2x5x8 and 3x4x8 boards [186], as well as a 3x3x9 version of shogi [572].

  Ci2 -- Multiple boards
   Alice C and its variants might be considered restricted forms of 2x8x8 chess in which every moving unit must change boards after its move!  Alice C uses two boards. The first begins with the standard array; the second is vacant. A move consists of playing any legal move on either board, then transferring the moving unit from its landing square to the same square (which must be vacant) on the other board. The moving unit can only capture a unit on the board it starts on; checks and interpositions can only take effect on the board it finishes on. A unit can only guard friendly units on the other board. Castling transfers both king and rook to the second board; the king can pass over squares guarded or occupied on board 2 while castling. Units on either board can guard or block the enemy king's flight squares; many quick mates are possible (1 d4 Nf6 2 Qd6 e6 3 Qe5/1#; 1 e4 d5 2 Bb5 dxe4/1 3 Ba4/1#).  Note that moves finishing on board 1 are suffixed /1). In diagrams, a single board is used; units on board 2 are shown inverted.
   One variant of Alice [273] is played with two 4x8 boards -- this can be played on an orthodox board by imagining it cut into two halves. Another variant is Ms. Alice C, in which any piece (not a pawn) can make a zero move, transferring itself to its starting square on the other board. A king cannot escape check by a zero move; a king or rook which has made a zero move cannot castle. One foolsmate is 1 Qd1 d5 2 Qa4/1#).  In a third variant, the black army starts on board 2 instead of 1 -- this eliminates many of the shorter foolsmates. Duo C is an even freer version of Ms. Alice. Variations using three or more boards have also been proposed.
   Leo Nadvorney is a great advocate of, and expert in, Alice C. He published an informal collection of over 40 games in about 1975. He coined the term 'discheshired check' for the capture of a pinned unit, with the capturing unit disappearing to the other board. He also combined Alice with his version of Spherical C to make Sphericalice, played on two Alice boards using spherical movement on each board.

  Ci3 -- Four or more dimensions
   Sphinx C is a four-dimensional chess played on a 3x3 array of 4x4 boards. A unit can make a normal move on its 4x4 board, or move to the same square on a different 4x4 board by a move corresponding to a normal move on the 3x3 'superboard' (e.g. a rook at A1b2 may move to e.g. A1a2, A1c2, A1b1, A1b3, B1b2, or A2b2. Knights make queen moves on the 3x3 board (otherwise they could never reach B2). Pawns move one square or one board forward, and capture diagonally forward in the same way. They promote at the far end of any far board (e.g. a White pawn at A3c4). The game can also be played as mock or giveaway. If played for mate, perpetual check wins; kings may also be confined to their initial 4x4's. The board may also be reduced to 2x2x4x4 (playable on an orthodox 8x8).
   In Dawson's 4-Dimensional C, the board is 4x4x4x4 (usually shown as a 4x4 array of 4x4 boards). The balloon is a four-dimensional version of the unicorn (e.g.  moving from B3c2 to A2b1/A4b3/C2d1/C4d3).  Six Dimensional C is a complex game which can be represented on an orthodox 8x8 board. Ecila C is a six-dimensional game, analogous to Sphinx C, played on a 2x2x2 array of 2x2x2 or 3x3x3 boards.

Cj -- Non-planar (edgeless and semi-edgeless) boards
   Non-planar boards are boards in which a unit need not automatically stop when it reaches the edge of the board, but can continue moving in some specified direction. Nadvorney (NA185) and Betza (NA253) showed how movement on many of these boards can be pictured by imagining copies of the board placed edge to edge in certain manners (see diagrams below).
  Cj1 -- Cylindrical boards
    c7d7|e7f7g7h7a7b7c7d7|e7f7    g2h2|a2b2c2d2e2f2g2h2|a2b2
    c8d8|e8f8g8h8a8b8c8d8|e8f8    g1h1|a1b1c1d1e1f1g1h1|a1b1
    g8h8|a8b8c8d8e8f8g8h8|a8b8    g8h8|a8b8c8d8e8f8g8h8|a8b8
    g7h7|a7b7c7d7e7f7g7h7|a7b7    g7h7|a7b7c7d7e7f7g7h7|a7b7
    g6h6|a6b6c6d6e6f6g6h6|a6b6    g6h6|a6b6c6d6e6f6g6h6|a6b6
    g5h5|a5b5c5d5e5f5g5h5|a5b5    g5h5|a5b5c5d5e5f5g5h5|a5b5
    g4h4|a4b4c4d4e4f4g4h4|a4b4    g4h4|a4b4c4d4e4f4g4h4|a4b4
    g3h3|a3b3c3d3e3f3g3h3|a3b3    g3h3|a3b3c3d3e3f3g3h3|a3b3
    g2h2|a2b2c2d2e2f2g2h2|a2b2    g2h2|a2b2c2d2e2f2g2h2|a2b2
    g1h1|a1b1c1d1e1f1g1h1|a1b1    g1h1|a1b1c1d1e1f1g1h1|a1b1
    c1d1|e1f1g1h1a1b1c1d1|e1f1    g8h8|a8b8c8d8e8f8g8h8|a8b8
    c2d2|e2f2g2h2a2b2c2d2|e2f2    g7h7|a7b7c7d7e7f7g7h7|a7b7
     NOST Spherical C [421]       Toroidal/Cylinder C

   The best known non-planar CV is Cylinder C, in which the a and h files are imagined to be joined. Units can cross the left and right edges in the diagram above right (but not the top and bottom edges), so that a rook can move b2-a2-h2-g2 (even if e.g. e2 is blocked), and a bishop can move from a5 to h4-g3-f2-e1 or h6-g7-f8. Infinite moves and moves returning to the starting square are usually prohibited. Kings are permitted to castle with either rook around the edge; C-O-O denotes the White move Kc1/Rh1(via a1)d1; C-O-O-O denotes Kg1/Ra1(via h1)f1. The board edges can instead be joined horizontally (connecting ranks 1 and 8), producing Horizontal Cylinder C (units can cross only the top and bottom edges in the diagram). This is common in problems but unplayable in the standard array. A playable form could be adapted from some variety of round chess, though the latter is perhaps easier to visualize. My suggested array for an 8x8 game (all pawns move forward with doublestep, promoting on their eighth rank) is given in the Index. This might also be usable for Toroidal C.
   The Toroidal C (also called Anchor-Ring) board, in which a cylindrical board has its two ends connected like a torus (doughnut shape), has also long been used for problems. In the diagram, units can cross all four edges. The orthodox array cannot be used, but Tylor has devised a playable one. Another playable array is found in Megachess, in which each side has a row of eight pieces entirely surrounded by pawns on a 14x14 toroidal board. Pawns in both games move in a direction away from their home piece row, promoting there in Toroidal C and on the opponent's home piece row in Megachess.
   Phil Cohen points out the difficulties of mating on a toroidal board (at least 2 rooks or 4 minor pieces are needed), and suggests that stalemating the opponent and/or reducing him to a bare king should be considered wins (or alternatively, allowing the king to move orthogonally only -- i.e., as wazir -- which allows K and Q to mate lone K). He has also suggested Toroidal Pre-Chess (see Cb1).
   Moebius C is a cylindrical chess in which the board is given a half twist before the a and h files are joined, so that a2 is adjacent to h7. More exotic methods of joining the edges are found in Oblique Cylinder C, Klein Bottle C, Ladder Board C, Corner Wrap C, Right-Angle C, and All-Angle C.
   In Spherical C, the board is imagined to be wrapped around a sphere. Units leaving a side edge reappear on the opposite edge as in Cylinder; units leaving an end edge ('pole') reappear elsewhere on the same edge. There are at least two versions (by Miller and Nadvorney), differing in how bishops cross the poles. The diagram above left shows how units cross edges in the NOST version. The original form, invented by Grayber, is mentioned but not described in NJEI; I do not know whether his version is the same as either of the above, or yet a third form.  Dekle has adapted shogi to a 10x9 spherical board [575].

  Cj2 -- Round (circular) chesses
   The vertically cylindrical 8x8 board has been projected onto a flat surface to make Wagon Wheel C, having 8 rings of eight squares each (the rings are equivalent to ranks, the radii (spokes) to files). White is arranged as normal on the two outermost rings, Black on the two innermost. A commercial version of this is the 1965 Global C. Orbital C [432] is an unusual form of round chess, played with three or four armies side-by-side (separated by barriers or missing squares) on the outer rings of special 6x30 or 6x32 boards.
   Most round chesses, however, are projections of a horizontal cylinder (in which rings are files and radii are ranks). The most common round board is the 4x16 board pictured on the cover. This was first used in Byzantine C, a Shatranj variant (Citadel Zatrikion is a similar game in which the center is divided into four citadels). The 4x16 has also been used for Circular C, a variant using modern moves. Verney invented three- and four-player versions for a 4-ringed board having 24 and 32 radii respectively (each army takes up 4 radii, with 4 empty radii between each pair of adjacent armies). Because of their ability to move around a ring, rooks are worth (according to JENO) about 9 pawns, queens 12. The 1985 version of Global C is an 8x14 round board with each side having 8 pieces and 16 pawns, with a full radius of pieces surrounded on both sides by pawns. Four empty ranks separate the armies on each side.
   Parton devised Jabberwocky C, his own version of round chess, played on the intersections of a circular board with special pieces, described loosely (no arrays are given) in the two cited sources.
   Chess in the Round is a commercial variant which allows a sort of circular movement by dividing the board into four concentric rings (ah18, bg27, cf36, and de45), allowing rooks and queens to move freely around a ring (see Orbital C [431]). A similar idea is used in Racetrack C, which adds three extra files to each side of the 8x8 board.

  Cj3 -- Rebound chesses
    b7a7|a7b7c7d7e7f7g7h7|h7g7    c6b6|a6b6c6d6e6f6g6h6|g6f6
    b8a8|a8b8c8d8e8f8g8h8|h8g8    c7b7|a7b7c7d7e7f7g7h7|g7f7
    b8a8|a8b8c8d8e8f8g8h8|h8g8    c8b8|a8b8c8d8e8f8g8h8|g8f8
    b7a7|a7b7c7d7e7f7g7h7|h7g7    c7b7|a7b7c7d7e7f7g7h7|g7f7
    b6a6|a6b6c6d6e6f6g6h6|h6g6    c6b6|a6b6c6d6e6f6g6h6|g6f6
    b5a5|a5b5c5d5e5f5g5h5|h5g5    c5b5|a5b5c5d5e5f5g5h5|g5f5
    b4a4|a4b4c4d4e4f4g4h4|h4g4    c4b4|a4b4c4d4e4f4g4h4|g4f4
    b3a3|a3b3c3d3e3f3g3h3|h3g3    c3b3|a3b3c3d3e3f3g3h3|g3f3
    b2a2|a2b2c2d2e2f2g2h2|h2g2    c2b2|a2b2c2d2e2f2g2h2|g2f2
    b1a1|a1b1c1d1e1f1g1h1|h1g1    c1b1|a1b1c1d1e1f1g1h1|g1f1
    b1a1|a1b1c1d1e1f1g1h1|h1g1    c2b2|a2b2c2d2e2f2g2h2|g2f2
    b2a2|a2b2c2d2e2f2g2h2|h2g2    c3b3|a3b3c3d3e3f3g3h3|g3f3

     Returner Board C [517]       Billiards C [60]

   In Billiards C (also called French Billiards C), all units can bounce off the four board edges. (Examples: Bc1-a3-f8-h6-e3, Re1-e8-e5, Nb1-a3-b5, Nf3-h4-f5, Bd5-a8-b7). Multiple rebounds are allowed. Units may capture on an edge and rebound; captures off the edge end the move (a B or Q can make up to five captures in a move). Rebounds are optional; a unit may stop on an edge square. Infinite rebounds and rebounds which do not change the position are illegal (a piece may only stop on its starting square if it has captured). Knights cannot rebound from corners. Pawns can rebound (one square) only when capturing to the a or h file; the rebound move may be a capture also (b5xa4-b3 or g4xh5xg6). Kings can rebound one square away from an edge (Kf2-g1-h2-g3), but cannot pass through check. A pinned unit can move if it rebounds to capture the pinning unit or return to the pin line. Berthomeau's more playable 1957 revision permits only one capture per turn (a unit after capturing may continue to move/rebound, but cannot capture on the same move and thus does not threaten the enemy king), but allows knights to rebound from corners (Nb3-a1-c2).
   Bruce's Billiards C is played on an 8x7 board, allowing two bishops to attack every square of the board. The original form of Billiards was Pocket Billiards C, also called Dutch Billiards C. Corner squares (a1/a8/h1/h8) are POCKETS; units moving there are 'potted' and returned to their starting squares. Both games otherwise follow the French rules.
   A number of other variants of Billiards have been devised. Italian Billiards C is a progressive variant in which only bishops and queens rebound, and capturing ends the move. Reflection C allows rebounds off the left and right edges only. Camelot C is a modification of Billiards on an 8x12 (rotated Courier) board. In Bouncy C, rooks do not rebound; Q/B/K/P rebound diagonally as in ordinary Billiards. Knights may rebound at any angle except the angle they hit the edge at (a knight moving from b1 to a3 may rebound to c2 or c4 as well as b5). Knightrider Bouncy replaces knights with nightriders, allowing them also to bounce freely -- see sample game 6. The nightrider in this game is enormously powerful -- from the center of an empty board it can reach 53 of the 63 other squares! Ricochet C is a group of variants in which units can bounce off other units as well as board edges. In Returner Board C, units bounce off the sides as if traveling through square centers (a typical bishop rebound might be c6-a4-a3-c1-d1-f3 -- see the diagram above).

Ck -- Mosaic C (boards not tiled with squares)
   Paletta, in Chess Spectrum Newsletter 2, describes a group of CV's, which he collectively calls Mosaic Chess, played on boards composed of hexagons, diamonds, and other shapes. Many boards composed of triangular or hexagonal cells were designed for three-player variants -- I classify these here rather than in Cy1 -- in general these boards are triangular or hexagonal in overall shape as well. Other boards have been designed for two-handed play.

  Ck1 -- Hexagonally tiled boards
   In most forms of hexagonal chess, the rooks move through cell sides, along straight rows of cells in any of six directions. Bishops move through cell corners along a series of cells of the same color (see the board on the cover), so three bishops instead of two are needed to cover the whole board. Knights move to any of the 12 cells a distance of three cells away (except those that can be reached by a rook). Queens combine the power of a rook and bishop. Kings have (depending on the variant) either a wazir move (to any of the six nearest cells) or a full king move (to the twelve nearest). A queen can mate a wazir-king unassisted; queen and full king can mate full king (rook and full king can also -- a somewhat trickier mate). Pawns move one cell straight forward, and capture one cell diagonally forward, in both cases to a cell of another color -- as a rook, not as a bishop.
   Perhaps the hexagonal CV closest to orthodox chess is De Vasa's C, played on a 9x8 parallelogram with full king, three bishops and nine pawns (see the board and array on the back cover, lower left). Since pawns face a cell vertex instead of a side, they are more powerful, having two forward directions for movement and three for (bishop-like) capture. A pawn at d4 can move to d5 or e5, and capture at c5, e6, or f5. Pawns on their initial rank can doublestep (g7 to e5 or g5). Other moves are conventional.
   The most successful form is Hexagonal C (invented by Glinski), which has spawned organized play as well as a number of publications. It is played on an order-6 hexagon with conventional moves (full king). Baskerville's C is played on a roughly rectangular 11x8 board of 83 cells (a recent CV on a similar board is Chessnik) -- the king has the wazir move. There are only two bishops per side, which stand on the same color cell! Hexchess uses an order-5 hexagon, with very unusual moves. Ludus Chessunculus is played on the same board with a simple set of pieces (12 units per side). Dekle has devised pseudo-hexagonal boards made up of squares or crosses in a 'brick wall' pattern [163, 371], as well as a hexagonal version of shogi [284].
   Several hexagonal variants have versions for two and three players, sometimes on different boards. Hyperchess uses a peanut-shaped board for two players, and a large triangle with corners truncated for three players. Hexachess uses similar boards of slightly different sizes. HEXChess uses an order-7 hexagon in both versions, but is also flawed in only having two bishops per side. Two variants devised for three players only are Wellisch 3-Handed C, played on the order-6 hexagon shown on the front cover, and Tri-Chess [631], played on an order-9 hexagon. Wellisch has unorthodox moves -- there are no bishops, knights move one square diagonally (i.e. as a fers), queens combine fers and rook, kings move as wazir, and pawns moves as in De Vasa, but capture as they move. See also Plex (Cy3), a six-handed variant.

  Ck2 -- Triangularly tiled boards
   Moeser and Paletta both suggest the term Triagonal C for a variant played on a board composed of equilateral triangles, but neither gives a full description (Moeser sketches some possible moves). The only fully described CV's on triangulated boards have been devised by Dekle [629, 633], who has also adapted shogi to a triangular board [637].

  Ck3 -- Other tilings
   Paletta devised a number of unorthodox boards tiled with diamonds or other shapes. We will not attempt to describe Hexagram C, Hexstar C, Octostar C, or Rhombic C. Orion C (see WGR3) is an adaptation of chess to the rotary Orion game system. Triboard C is Dekle's 2-handed game played on the three-handed board of [615/616].
   Circle C is played on a roughly diamond-shaped board made up of hexagons, squares, and triangles (the same tiling used in the board game Kensington and the Birds and the Bees puzzle in WGR9). Units have various powers combining straight and circular moves. The inventor, A. F. Stanonis, published, between 1963 and 1977, a number of issues of a magazine devoted to variants of this game played on boards of various sizes, and using pieces with many combinations of moves.

Cl -- Boards modifying movement
  Cl1 -- Restricted movement boards
   In Grid C, nine grid lines divide the board into 16 2x2 regions (ab12, ab34, ..., gh78). A unit in moving must cross at least one grid line, finishing in a region different from the one it started in. Several variants have been devised to improve mobility (especially of pawns). Paletta in CS1 suggests that pawns move normally, ignoring gridlines.  DG (Displaced Grid) Chess shifts the grid one square diagonally, making 25 regions (a1/a8/h1/h8 are single square regions; there are 12 two-square regions). Grid has also been combined with Berolina pawns (Cd1) to form Berolina Grid C (also known as Berogrid or Gridolina); this is the most popular combination game in NOST. Berolina pawns are much more mobile in Grid than orthodox pawns. Other popular combinations are U-Grid (Co1) and Plaid C (Scottish Grid). A foolsmate in Plaid C is 1 e4 2?? d5 Na6 3 Bxa6 Bxb7 Bc6#. In cylindrical variants of Grid C, the board edges are also considered grid lines.
   In Slippery Center C, the center squares de45 are considered to be slippery (perhaps covered with ice?) -- no unit may stop on one of these squares, but instead must continue in the same direction until reaching a normal square -- B/R/Q can go further if desired (e.g. Nf3b5, d3xf5, Kc3f6, Qd1d6/d7/d8. There is no e.p., and de45 are never considered guarded. In Very Slippery Center C, units hitting the slippery squares turn 90 degrees in either direction before sliding off to a normal square, e.g. Qg3a1/h8, Nd3c6/g4, e3c4/f4). In Skid Row C, the entire 4th and 5th ranks are slippery; units slide off as in Slippery Center.

  Cl2 -- Boards increasing or altering movement
   In some variants, the square on which a unit stands determines how it may move. In Lumberjack C, pawns are normal. Each piece has no intrinsic movement power, but moves in the manner of the piece which starts on the file on which it stands (a unit on the a or h file moves as a rook, on b or g file as a knight, on c or f file as a bishop, on d file as a queen, on e file as a king). The king is subject to check wherever it stands; other units on the e file are not royal. There is also a Giveaway form of Lumberjack (a stalemated player wins) called Fishaway; it is more complex than regular Giveaway because of the variable powers of the pieces. An earlier game, Free C, uses the same scheme (excluding kings and pawns), but the file-based movement power is in addition to the unit's normal power; a rook standing on the c or f file moves as a queen.
   A somewhat different game is the commercial variant Smess (later All The King's Men). The 7x8 board is marked with a varying pattern of arrows -- the arrow(s) in each square indicate the direction(s) in which a unit standing there can move. Units are divided into single step (8 per side, including a royal piece) and 4 long range units.
   Chesquerque is played on the Alquerque board (9x9 intersections with a superimposed pattern of diagonal lines) which both expands and limits the moves of various units. In Domino C, a grid of 32 dominoes is superimposed on the 8x8 board (a12, a34, ..., h78). All units have their normal moves; bishops and knights can also move from one side of a domino to the other in place of a normal move. In Frontier C, queens move a maximum of two squares. When any piece except a king starts its move in the enemy half of the board (5th rank or beyond), its powers are altered. Knights move and capture as (limited) queens and vice versa; rooks move and capture as bishops and vice versa. In Quadrant C, pieces move normally when they start and end their move in the same quarter of the board (ad14, ad58, eh14, eh58); on moves crossing the line between the 4th/5th ranks or d/e files, they alter powers as in Frontier C. See also Sniper C (Cf2) and Wizard C (Cq1).

Cm -- Miscellaneous board modifications
  Cm1 -- Boards with moving parts
   Rotation chess is the generic name for a group of variants in which one or more square areas of the board (usually 2x2, but sometimes 3x3 (Megarotation) or 4x4 (Lazy Susan and ARQ)) can be rotated each turn, either automatically or at the discretion of the players. Of course the board itself does not actually move; rotation is simulated by repositioning the units within the rotated area.
   The oldest of the rotation chesses is Actuated Revolving Center (ARC) Chess, in which the center 2x2 region rotates 90 degrees clockwise whenever a unit ends its turn in that region. Actuated Revolving Grid C is a form of Grid C (Cl1) with rotation. After every move, the 2x2 grid square where the moving unit finishes its move rotates 90 degrees clockwise. In Actuated Revolving Quarterboard C, the 4x4 quadrant where the moving unit lands rotates (moves need not cross a quadrant line).   Variants are described in the index by specifying the squares which may rotate, direction of rotation, and the conditions under which a square rotates. There are five ways a move may relate to a region; these are designated by the terms Across, External, Into, Out of, and Upon, abbreviated by the vowels AEIOU (see Additional Rules for definitions). Permament rotation (designated P) occurs every half move regardless of what move is made. In most forms of rotation chess, the king must be out of check when a player's turn ends; a player may put his own king into check or leave it there if an immediate rotation removes the check.
   Besides the Actuated variants, there is Free Rotation C (any 2x2 area containing the landing square of the moving unit can be rotated 90 degrees in either direction), Restricted Rotation C (as Free, but a region containing one or more enemy units cannot be rotated), and Megarotation C (3x3 regions are rotated -- this may be played Free or Restricted). In Lazy Susan C, the center 4x4 (cf36) rotates 90 degrees clockwise after every half-move (in Double Lazy Susan C, the center 2x2 (de45) rotates anticlockwise instead of clockwise). The number of possible variants of rotation chess is almost unlimited.
   In Pinwheel C, all 16 regions of a Grid board rotate every turn. In Orbital C [431], there are four rotating rings which rotate 90 degrees after every move. Every move must end on a ring different from the one containing the starting square. Brownian Motion C uses a closed knight's tour to reposition the units after each half-move (each unit moving to the next highest numbered square -- a variant of this is List C). All of these are virtually unplayable without a computer to show the new board position after each move.
   A set of variants (under the general name Rotofile C) were devised by Gutzwiller and Moeser, in which the 8 files could be shifted north and south, pivoted 90 degrees, or shifted from one side of the board to the other. See Index entries: 13, 311, 389, 461, 527, 585, 619.

  Cm2 -- Boards altered during play
   Two new commercial variants, Choiss and Schach Plus, involve a board which is built before movement begins. The equipment in both games consists of a standard set of units, and 64 independent squares, half black and half white. In Choiss, the whole board is built, then units are placed and play begins. In Schach Plus, squares can be placed on the growing board with units on them. The board in both games generally ends up in a very irregular shape.
   Instead of growing or moving, the board can shrink. In Shrinking Board C, whenever an edge rank or file is vacated, it disappears from the board. Pawns cannot promote if their eighth rank disappears. (Boyer suggests starting from the 15th or 20th move of a master game). In Cheshire Cat C, each square can be occupied only once -- any occupied square disappears (but can be passed over) as soon as it is vacated. To avoid isolation, the king moves like a queen on its first move.
   Merger C allows adjacent squares to be merged into single realms. Movement is unaffected except that only one unit may occupy a realm. An enemy unit is captured by moving to any square of the realm it is in (as in some forms of Cp1). Hyperspace C is a variant in which any two board squares can be 'linked', allowing any unit to travel from one to the other as a move. Links can also be cut.

  Cm3 -- Special effects on selected squares
   Two variants allow squares selected before the game to have special effects. In Joyous C, each player openly selects one square to cause promotion (N => B=> R => Q), another to cause demotion, to any piece (except king) of either color landing there. In Minefield C, each player secretly writes down 6 squares which are mined. Any unit (except a pawn or king) which lands a square mined by the opponent is destroyed -- the square is safe after the mine 'explodes'. In Pyramid C, each player places one pyramid, an immobile block which can only be captured by a knight.

Modification of Basic Movement Rules

Cn -- More than one move per turn
  Cn1 -- Fixed-length turn series
   Marseillais C is a double-move variation. Each player makes two moves per turn, with the same or different units. If check is given with the first move, the second is not played; in either case, check must be removed with the first move, or checkmate results. A player may not place his own king in check with either move. Stalemate is a draw; a player may move into stalemate on his first move of a pair. Under AISE rules, en passant is permitted only when a pawn makes a doublestep on the second move of a pair, and the opponent captures the pawn on his first move of the next pair.  White has a strong advantage in Marseillais, which is decreased in Balanced Marseillais C. White only makes one move on his first turn; each player makes two moves a turn thereafter.  NOST rules forbid e.p.; AISE follows the same rule mentioned above. 
   Doublemove C is another double-move variation, in which the object is to capture the king -- check is ignored, so kings can move or castle across/onto attacked squares (e.g. capturing a guarded unit or even the enemy king!).  The move pattern is as in Balanced Marseillais (1,2,2,2,...). E.p. is illegal. Every turn must change the position; i.e. a player cannot move a unit to a new square and then back to its starting square, unless a capture or promotion is made. If a player is unable to make two legal moves on his turn, the game is drawn by stalemate (this is rare, since check does not exist -- a player may be forced to put his king en prise and lose). A balanced multimove pattern [45] (1,2,3,3,... or 1,2,3,4,4,...) can be used in three- and four-handed games (see Cy).
   Citizen C is a variant of Marseillais in which the first move must be made with a piece, and the second (optional) can be made only with a pawn (thus pawn moves cannot remove check). Captures or checks on the first move end a player's turn. E.p. is illegal. A player with no legal piece move draws by stalemate.
   Triplets is a triplemove chess variation. (In this paragraph, piece specifically excludes king as well as pawn). On the first move, each player moves a pawn. On the second move, each player moves a pawn and a piece in either order. On the third and succeeding moves, each player moves a pawn, a piece, and the king, in any order. A player may thus castle (counted as a king move only), if at all, only to the kingside, and only on his third move. A player who cannot make all three parts of his move loses by stalemate (blocking all of the opponent's remaining pawns is a common method of winning). Check may be relieved by any of the three parts; a player may put/leave his king in check with one part if a later part removes check. If a pawn promotes, the promoted piece may make the piece-move of the same turn. Phil Cohen suggests using the king as an attacking piece from the start, since checks don't gain time as in orthochess. Triplets is unusual in that draws are impossible, except by agreement.  The championship game from the first  NOST tournament is given as Sample Game 11.
   Quest-Chess, based by Donald Benge on his popular abstract wargame Conquest (see WGR2), allows players to make ten moves per turn (five on White's first). A unit may not move more than once per turn unless it captures or gives check (in either case the opponent has the right to immediately recapture if possible or otherwise parry a check). Detailed rules, including a four-player version, Quatre Quest-Chess (see Cy2), can be obtained from Benge.

Cn2 -- Variable-length turn series
   In Swarm C, a player must move every unit once per turn if possible (but blocking or pinning one's own units as in English Progressive is allowed). Units may move in any order, but check must be removed on the first move of the turn. Castling is a king move only. Any number of checks may be given (check does not end the turn), and checkmate OR capturing the enemy king wins. White has a large advantage.
   In Sputnik C, any rook, bishop, or knight starting a turn in the enemy half of the board (own 5th rank or beyond) is a sputnik. On a player's turn, he moves any desired number of his sputniks (even zero), then must move exactly one non-sputnik (Q/K/P, or R/N/B starting in his own half). A sputnik returning to its own half becomes a normal unit on the next turn. There is no limit to how many times a R/N/B may cross from one half to the other during a game.
   Threesum C allows a player on his turn to move up to three units, but they can only move a total of three (any combination of orthogonal and diagonal) squares. Knight moves count two squares; castling counts one. On each half-turn of Multimove Dice C (see also Co3), a die is rolled to determine the number of moves allowed for the moving player (with a maximum of four moves, permitted on a roll of 4/5/6). Using the same throw for White and Black on each full turn reduces the element of luck. Chess as a Wargame is a multimove, multifire CV somewhat similar to Rifle C (Cu2).
 
Cn3 -- Progressive
   The most popular group of variants are called progressive. White begins by making one move, Black replies with two moves, White makes three, etc., the number of moves per turn increasing by one for each series. Each series is consecutively numbered, corresponding with the allotted number of moves (see sample games). The number of moves allotted does not change even if the previous series was shortened (e.g. by an early check). A player may not expose his own king to check during a series, and must get out of check with the first move of his series, or he is checkmated. If a player runs out of legal moves before making his allotted number of moves, the game is drawn by stalemate.  Draws by repetition are not allowed.
   There are several main forms of progressive. In Scottish, the original form, a player's turn ends if he gives check before the end of a series. NOST rules for Scottish forbid en passant capture. In the Italian variation adopted by AISE, a player cannot give check before the last move of a sequence.  This can give rise to so-called progressive mate -- if the only move(s) to get out of check would put the opponent in check, the player in check is mated.  A common type of checkmate is one in which the mated king is pinned against one of his own pieces by the opposing king. See sample game 8 for an example of this.  If a player begins her series not in check, or removes a check (legally, without giving check) with the first move of her series, but runs out of legal (non-checking) moves before completing her series, the game is drawn by stalemate.  AISE allows en passant capture. If a pawn makes a doublestep move, does not move further forward on the same series, and the square behind it is unoccupied at the end of that series, the opponent may capture it en passant on the first move of the following sequence. AISE also allows a draw to be claimed if ten series pass without a capture or a pawn move, unless one side can demonstrate a forced win (this is similar to the 50-move rule in chess). In practice the Scottish and Italian variants are fairly similar, with the same openings being usable in both forms. In many cases, a progressive mate in Italian will lead to a win in Scottish anyway, since the opponent loses the rest of his series.
   In Scottish Modern C (unrelated to 393-395), a turn series ends at any time when a unit ends its move on an attacked square; otherwise as Scottish. This is a treacherous game; Black loses after 1 e4 2 e5 Nh6 (see NA178), a defense which has been used in regular Scottish games in NOST (though not in AISE progressive games). Another form of Scottish is The Bank of Scotland, in which the number of moves per turn does not increase automatically. Check may only be given on the last move of a series (and must be removed on the first move of the opponent's next series), and earns the player giving check one extra move per turn, beginning with her next series. There are two forms; the Main Branch is played like standard Scottish, the Modern Branch like Scottish Modern. Sacrificing a piece for a check to gain an extra move is a common tactic; indeed, White may have a sure win in the Main Branch by gaining one check after another (see Presto C, Cx5). A plausible line of play is 1 Nc3 c62 Ne4 e6 3 Nd6+ Bxd6 4 e3,Nh3 Qf6 5 Qh5,Qxf7+ Qxf7 6 Be2,Bh5,Bxf7+ Kd8 7 b3,Ba3,bxd6,Bc7+ Kxc7 8 f4,f5,fxe6,e7,e8=Q Nf6 9 Qe7,c4,c5,Nf4,Ne6#.  Can anyone suggest a viable defense for Black?
   Quite different from all of the above variants is English Progressive, invented by some unknown player in England during the past decade. Tony Gardner has codified a set of rules which have been adopted for NOST play. Rules follow Scottish (no e.p., early check ends turn; 10 series draw rule as in Italian), but with one crucial exception...    Each series consists of one or more sequences. In each sequence, every unit which can move must do so (in any desired order), or be blocked or pinned so as to be unable to move. A sequence ends when every unit has either moved once or is unable to move. If there are moves remaining in the turn allotment, another sequence begins, with each unit again only able to move once. Castling counts as only one move in the series, but counts as both a king and a rook move in the current sequence. A pawn which promotes during a sequence cannot move again until the next sequence. Normally, multiple sequence moves do not begin until well into the game (perhaps series 10 or so). English Progressive games usually run somewhat longer than ordinary Progressive.  [David Pritchard's book Brain Games mentions a different variant in which no unit may move more than twice per turn.]
   Gardner offers several useful tactical hints. It is quite legal to block or pin one's own units to end a sequence more quickly, gaining extra moves for prominent pieces. It is possible to move a unit twice in a row if you move it as the last move of one sequence, and the first move of the next sequence. In the middlegame and endgame, placing your king on a file adjacent to an opposing pawn, where the pawn will give check when it advances, can end the opponent's turn early. Finally, be alert to the possibility of underpromotion to avoid a turn-ending check. Some examples of Gardner's tactics are given in sample game 3.
   Instead of the simple 1,2,3,... progression of standard progressive chesses, other sequences of move lengths have been tried. Parallel Progressive uses the sequence 1,1,2,2,3,3,..., but this gives White a large advantage. More balanced is Slow Scotch (1,1,1,2,2,2,3,3,3...).  Another idea is Cyclic Progressive, setting a maximum move length (6 is a good value), and varying between 1 and the maximum (1,2,3,4,5,6,5,4,3,2, 1,2,3...). In Very Scotch, when a player's series is shortened by check (intentional or involuntary), the opponent is allowed one more move than the player giving check just made; series length increases one per move thereafter until shortened by check again (in a sense the opposite of Bank of Scotland).
   Malcolm Horne mentions that he has tried progressive shogi and progressive xiang qi; he says they don't work as well as orthodox chess.  See also combination games [473-476, 538-543, 655].

Co -- Movement limitations (see also Cl1)
  Co1 -- Limited choice of moves
   One group of variants in which the choice of moves is limited includes Refusal C and Compromise C. In Refusal, a player proposes to make a particular move, and the opponent has the right to refuse it if desired. If he refuses, the player moving then makes a different move, which must be accepted. A player may not put/leave his king in check (intending to refusing the capture of it). Two different pawn promotions are considered different moves. If only one legal move is available, the player must make it -- the opponent cannot refuse. A move may be proposed (and rejected) any number of times. In recording games, the score should show rejected moves in parentheses. Refusal works well over-the-board, and has an interesting psychological aspect -- do you make a second-best move, hoping that the opponent will refuse, and you can substitute the best move?
   In postal play, the standard form of Refusal adds greatly to playing time, since many moves will be rejected and replaced. An alternate form, in which the number of refusals per game is limited (e.g. 10 per player -- the stronger player can be given a smaller number as a handicap) can be played, but the most popular version for postal play is Compromise, exactly like Refusal, except that a player sends two moves per turn, and the opponent selects which one he prefers the player to make, simultaneously sending two choices for his own move following.
   Double Option is an early form of Compromise in which a player must always send two moves (the second may be 'Mate' or 'Resigns'). I.e., when a player has a move which gives mate, he may force the opponent to accept, and when he has only one move available, he loses (unless it is mate!). Choice C is the same as Compromise, except that a player must propose five moves per turn instead of two. A variant of Compromise played at NV'90 is No-Entry C, which uses a coin in addition to the standard board and units. After each move, the moving player places the coin on any vacant square (he may leave it where last placed). The opponent cannot move to that square, but may pass over it. Captures cannot be prevented, but weak squares can be protected. A wilder version prohibits moves passing through the coin square (but knights may leap over it).
   In Proximity C, White makes his first move; thereafter each player must move the unit (or any of them if there is more than one) closest to the landing square of the opponent's last move. If none of the closest units can move, the player may make any move. In Maximummer C, each move must be the longest possible (or any of the equal longest). Distances in both of these games are Pythagorean (see GFC for details). Equidistant C is a restricted form of Balanced Marseillais C. White makes a single move, then on each half move thereafter, each player makes a move equal in distance to the opponent's last (e.g.  if the opponent moves diagonally, you must move the same number of squares diagonally, the same for orthogonal moves; a knight move must be answered by a knight move). On his second move, the player then makes any desired move of his own with a different unit. See Cr2 for movement restrictions based on neutral units.
   In Looking-Glass C, two boards are set up, considered to be mirror images of each other. A move on either board is permitted, and the reflected move is made on the opposite board. A king move on one board is mirrored by a queen move on the other board and vice versa; kings can thus move as queens (Qd1b3/Ke1g3), but kings cannot move into check on either board (and queens are consequentially uncapturable). Mate on either board wins.
   In One-Shot C, a unit can make a move of a given distance and direction twice per game -- once capturing, once non-capturing. Castling is an extra move power. E.g. each pawn can singlestep, doublestep, and capture once in each direction. En passant counts as a normal capture.  Pawns reaching the seventh rank promote to a new piece with a new full set of moves. Stalemating or checkmating the opponent wins. This game requires a record sheet showing all 402 possible moves for each side (Each K/Q/R/B/N/P has 18/112/56/52/16/4 moves respectively).
   In U-Chess, every move must be able to be written without ambiguity in descriptive notation, in three symbols or less, to be legal (e.g. PK4, QxR, OO, OOO, P=Q). A move is ambiguous (and therefore illegal) even if one of the two possibilities is illegal because it puts a player's own king into check. Check and mate do not count among the 3 symbols, and cannot be used to distinguish an otherwise ambiguous move. Pawns cannot promote by capture (PxR=Q e.g. is five symbols), but guard eighth rank squares against the enemy king (since PxK would end the game). Castling if legal is always unambiguous. En passant capture is legal if there is only one PxP possible. Some useful examples from NA190: In the position 1n2k1nR/2p2p2/16/5p2/r7/1K4P1/2r2B2, White can play KB3 (RxK ambiguous!) but not KxR. If White plays BN5, Black cannot answer PB3 or NB3 -- both are ambiguous even though one possibility is illegal. A foolstalemate is 1 PK4 PK4 2 PQ4 PQ4 3 NK2 NK2 4 NQ2 NQ2. U-Chess is a popular game in combination with other variants (e.g. U-Grid). A move illegal in U-Chess alone is illegal in any U-combination game. This game was apparently played in a similar form in the 1940's under the name Telegraph C.
   Marshall proposed Restriction C, similar to the checkers system of restriction openings (a standard set of cards from which one is drawn at random at the start of a game, giving the first few moves of the game for for both White and Black), but 46 of his 52 cards began with 1 e4! This resembles Postage Reducer Openings (used by NOST and other clubs), a set of openings (24 in NOST -- 7 moves for each player) from which players can select by agreement.
 
  Co2 -- Other movement restrictions
   A simple movement restriction suggested to bypass opening theory is No-Castling C. In Barrier C, no unit may move through a square on which it could legally be captured. A rider does not check an enemy king from a distance unless another friendly unit guards the adjacent square (WRe1 alone does not check BKe8, but does check if there is a WBh4). [Compare En Passant C]. In Madrasi C, units of the same species which mutually attack each other are immobilized (see also Cv3), but can be captured by other units. A pawn which doublesteps paralyzes an enemy fifth rank pawn next to it for one turn!
   In All-Connect C, the board begins empty. Players alternately place units on the board or move an already played unit (as in Cb2), but all units (of both colors) on the board at all times must be connected (orthogonally or diagonally) into a single group.
   In Hobbler C, B/R/Q cannot make a move of only one square. In Threespace C, they are limited to moves of three squares maximum. Kaissa (Cc5) also has maximum move lengths for some pieces. In Phillips Chessers, each piece has a maximum move length: 1 for king, 2 for queen ('circle'), 3 for bishop ('triangle'), 4 for rook ('square'). When capturing, pieces must move their maximum allowance, but can pass over occupied squares. When not capturing, they cannot leap, but may move any distance up to their maximum. The first move for each player must be a one- or two-square move. A king in check may escape by leaping over an adjacent friendly piece (as D or E) to a vacant unchecked square. The object is to capture the enemy king or move your king into the enemy thronesquare (see Cx6) -- this is legal even if the king is in check there.
   In No-Retreat C, no unit may make a backwards move (including diagonally) -- only forward or sideways -- until it reaches the eighth rank. Each unit reaching the eighth rank may make one backwards move during the game (it thus can give check). Presumably a stalemated player loses. In Checkers C, a unit may not move backwards or sideways until reaching the eighth rank -- then it can move freely in any direction.

  Co3 -- dice chess (semi-random move generation)
   One of the oldest forms of chess, Chaturaja, is a four-handed form of dice chess. Several variants have been invented in modern times. A simple form, given in JENO, is to roll one die per turn. 1 or 2 allows either the king or a pawn to move, 3/4/5/6 allow a move by Q/B/N/R respectively.  If no legal move is possible, roll again. A more elaborate form of this, Chance C, uses a special deck of cards marked with piece symbols and various wild cards. Another simple form of dice chess is to roll every move, allowing White to move when 2/4/6 are rolled, Black when 1/3/5 are rolled. This is similar to Cards C, in which a shuffled deck of cards are turned over one by one, White moving when a red card is turned up and Black when a black card is turned up. Multiple checks are allowed; the object is mate.
   An interesting form of dice chess, invented by British player Paul Novak, begins with five normal moves for each player. At the 6th move and thereafter, roll one die per turn (unless in check -- then make any move desired).  Move a unit of the type indicated by the die: 1 = P, 2 = N, 3 = B, 4 = R, 5 = Q, 6 = K. If you have no unit of the type shown, roll again. If you have a unit but cannot move it, you lose immediately (this rule forces players to develop quickly during the first five moves). Vegas Fun C uses two dice (marked with piece symbols and varying numbers of wildcards) per turn -- a unit shown on either die may be moved. There are three levels of play, which determine the relative balance between skill and luck -- they can also produce handicap games.
   Pinochle C is a combination of chess and two-handed pinochle. A chess unit may be moved for every card played (ATKQJ9 allow the player to move RNKQBP as in dice chess). The object is to score 1000 pinochle points or checkmate the opponent. See also Multimove Dice C (Cn2) and Deal C (Ca2).

Cp -- Multiple units per square
  Cp1 -- Units functioning independently
   Perhaps the first game to permit more than one unit to occupy the same square was Biplace C. This game allows two (not more) friendly units to occupy the same square (though they remain separate units, moving independently), or a friendly unit to pass through squares containing only one friendly unit. A unit entering a square containing two enemy units captures both. En passant is not permitted when the capture square is occupied. Note that castling may be the first move of the game! In Biplace C, as in other multiple-occupancy variants, a king may never enter a square attacked by an enemy unit, as the king is are not shielded from capture by friendly units in the same square.   Several multiple-occupancy variants have been devised in which any number of friendly units may occupy a square (in these variants, no unit may pass through a square occupied by units of either color). In Stacking C, a unit moving to a square containing one or more enemy units captures all of them (see Merger C, Cm2). In Gregarious C, the moving unit captures any selected one of the enemy units. Any number of units of both colors may thus occupy a square, but a unit may not move from a square containing more enemy units than friendly ones. In Duperchess, a unit entering a square containing occupied units may capture one unit, or may choose to capture none if desired; there is no movement limitation as in Gregarious C.
   Jet C is a commercial minichess (Ch2), played on a 3x3 or 4x4 board with multiple occupancy. Only the king, or king and queen (with pawns in their squares), are initially deployed; other units may be entered in the course of the game as in Cb2 variants.
   A board with extra-large squares (big enough to hold several pieces) has been suggested for any game involving multiple occupancy or combined units (including absorption variants (Cw1).

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   A well-known problem in recreational mathematics is to place eight white pieces (KQBBNNRR) on an 8x8 board so that every square (whether occupied or not) is guarded. It can be done using two bishops on the same color squares, but it is believed impossible to guard more than 63 squares if the bishops are on opposite colors. A curiosity is that if multiple occupancy is allowed, all 64 squares can be guarded with seven pieces (KQBBNRR) -- still with bishops on opposite colors -- by placing the knight on the same square as the queen (R7/7R/16/4Q&N3/3B4/2K2B2/8)!
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  Cp2 -- Combining units
   In Coronation C, when a player loses her queen, she may move a friendly bishop (by its normal move) to a square occupied by a friendly rook (or vice versa) to form a new queen. Promotion is normal; more than one queen is thereby permitted. In Empress C, a player may also form a chancellor (R + N) or cardinal (B + N) in an analogous manner, or promote a pawn to Q/C/X, but is limited to one combined piece at any time (Union C waives this limitation). In Confederate C, B/R/N can combine (moving together as a combined piece) or separate (one unit leaves the common square) at will. Combining/separating moves are possible (e.g. with Xa1,Bc1, one possible move is Ra1c1 ==> Na1, Qc1). In Combinating C, the queen is a counsellor (nonroyal unit moving as a king). V/R/B/N can form double or triple pieces at will (movable and capturable as a unit), but cannot split up when capturing. A combined rook cannot castle. In Auto-Additive C, a unit moving to a square containing a friendly unit forms a permanent unit with combined powers.  Friendly units are transparent.
   In Chessers, any piece (including a king) can move to a square containing a friendly pawn, combining with it to form a chesser, which can move forward only, using either its pawn or piece power. It can capture (but not be captured) en passant. A chesser may be split by moving the piece away in any direction, leaving the pawn on the starting square (not vice versa). If a chesser reaches the eighth rank, the pawn portion disappears.
   Another commercial CV is Crescendo C, which is more complicated than the variants in Cp1; up to three friendly units may be stacked in a square (using special interlocking pieces), allowing various types of combined moves. Ultrachess is a variant played on a special 12x12 board, in which knights may combine with friendly units. Variants in which units may combine in various ways include Nuclear C and Parton C (based on subatomic particle physics, as is its advanced version Fourfold Way C; pieces may break down into their component ferses and wazirs and be reconstituted, e.g. Q => 4F + 4W).

Cq -- New types of movement
  Cq1 -- Relay
   In a group of variants known collectively as relay chess, units relay their power to move and capture to other units. In the basic form, Relay C, all units except kings can relay or receive powers to/from other friendly units; i.e., a unit (except a king) can move, capture and check with the power of any friendly unit (except a king) guarding it (as well as its normal powers). Pawns cannot move, capture, or give check to the 1st or 8th rank via relay power. Pawns moving back to their 2nd rank regain their doublestep option.  Units receiving relay power from friendly pawns cannot promote but can move and capture (even en passant) as friendly pawns.
   The most popular form of relay chess is Knight Relay C, in which only knights relay their power. Any unit (except a king or another knight) can move, capture, and check like a knight (in addition to its normal power) whenever it is guarded by a friendly knight. There is no en passant. Pawns may promote to knight as usual. Knights (whether original or promoted) cannot capture, check, or be captured (this last rule was not part of the original version, but is now standard). Other rules are as in Relay.
   Bishop Relay is the same as Knight Relay, except that bishops instead of knights relay their powers to friendly units (b and g pawns cannot recieve bishop power until they have moved from their initial squares). Knight-Bishop Relay is a combination game in which one designated knight and bishop on each side have relay powers.
   In Ambivalent Knight Relay, knights relay their power to units of both sides; a unit 'attacked' by an enemy knight can also move or capture as a knight. A more complex version is Gnight Relay. Gnights behave as Ambivalent knights, but also relay capturing (and checking) power to other gnights of both colors. Gnights a knight move away from each other (of whatever color) can also be captured. In this variant a king may receive knight powers (and can thus check the enemy king, even if it is guarded). Pawns can move via knight moves to the 1st (from which they may doublestep) or 8th ranks (promoting in the latter case to gnight). En passant is permitted against pawns doublestepping from their 1st or 2nd rank. Pawns promoting by pawn moves can promote to Q/R/B as well as gnight or orthodox knight.   Relay has also been combined with other variants (e.g. [541]). In Knight-Relay Giveaway, kings can receive relay power just as any other unit; the object is to lose every unit except the (uncapturable) knights. Kings can also give relay power in Relay Giveaway C. In Co-Regal Knight-Relay (Cx4), neither kings nor queens can receive knight powers.   In Strange Relay C, all units (including kings and pawns) can only move with the power of friendly units which would guard them in orthochess. They can only capture with the power of enemy units which would attack them in orthochess (WQc6, BNb8, BQd8 -- White can capture by either Qxb8 or Qxd8 -- the latter capture is illegal in the related variant Moss C (see Ct1)). Pawns can move to their first or eighth rank (promoting on the latter). A stalemated player loses.
   In An-nan C, any unit with a friendly unit in the square behind it moves and captures with the power of the latter instead of its own. Other units, including those on first rank squares, move normally. This game is derived from a shogi variant played in an analogous way. In Exchanger C, a knight can exchange places with a friendly unit (even another knight) a knight's move away, in addition to its normal powers of movement and capture. In Wizard C, units adjacent to a king of either color (but not both kings) alter their powers as in Frontier C (Cl2).

  Cq2 -- Teleportation
   Teleportation C is a form of Exotic C (see Cq5) in which each unit except kings and pawns can be moved, once per game, to any vacant square on the board. In Teleport C, any unit may, instead of a normal move, transfer to the mirror-image square on the other half of the board (left-right; e.g., a unit on file c moves to the same rank on file f). In Rampage C, any unit may move or capture to any square which its side attacks more times than the opponent guards it. Pawns may promote via 'rampage' moves. Orthodox moves and captures are always permitted. A king must escape check by an orthodox move.
   In Anywhere C, any unit (except a king) may move to any vacant square (except a pawn to its first or eighth rank) in place of a normal move. Capturing moves (and therefore check), king moves, and pawn promotion moves must be orthodox. Presumably there is no en passant capture (doublestep is no longer a special move) or castling (unnecessary for rook, unhelpful for king). I would recommend playing the game in Balanced Marseillais fashion.

  Cq3 -- Crossings
   Robert Abbott's Crossings (A Gamut of Games) inspired two CV's.  Surge C allows one or more units adjacent in any orthogonal or diagonal line to move as a group along that line (in either direction), any number of unoccupied squares up to the number of units moving. E.g., units on a1/b2/c3 can move as far as d4/e5/f6 if all of those squares are vacant. A single unit can move to any adjacent empty square. Orthodox moves and captures are allowed as usual. Pawns can only promote by orthodox moves. Pawns on their first or second ranks can doublestep -- there is no en passant. Kings cannot cross over attacked squares.
   Crossings C (the original version, which Cohen feels is less chesslike) adds the capturing method of Crossings -- a group can move to the first square of a smaller enemy group (including a single unit), capturing it (e.g. a group at d1/d2/d3 can capture a single unit at d4, d5, or d6, unless both of the squares beyond are also occupied by enemy units). A threat to take the enemy king by crossings capture is check; orthodox captures and checks are allowed also. Surge/Crossings moves are written by giving the move of the rearmost unit (a Crossings C foolsmate is 1 e1g3 d8f6 2 d1f3 f8f5#).

  Cq4 -- Castling
   In chess, the king castles by moving two squares towards either rook, and the rook leaps over it to the square passed over by the king. In Highcastle C, every unit has the ability to castle (on either orthogonal or diagonal lines) with either a friendly or enemy unit. I.e., unit A moves two squares towards unit B, then places unit B on the square unit A crossed over (this move is denoted A*B) -- A must belong to the moving player; B can belong to either player; there must be at least two intervening squares, and all must be vacant. A king may cross attacked squares (as A or B) during castling. The enemy king may be castled (as B) into check. 'Castling' can be done at any time instead of an ordinary move. Capturing is only possible via an ordinary move; e.p. is abolished. Checks can be removed (in addition to normal ways) by castling away either the checked king or the checking unit. See sample game 5.

  Cq5 -- Miscellaneous forms of movement
   Exotic C is a family of games invented by Schmittberger in which each unit has a special power which can only be used once per game. At the start of the game, a checker is placed under each unit. When the unit has used its power, the checker is removed. Two simple forms of Exotic C are Teleportation C (Cq2) and Missile C (Cu2).
   In Halma C, any unit can make one or more non-capturing shortleaps over units of any colors (as in halma/Chinese checkers), in place of an orthodox move.
   Psychedelichess is a variant in which four extra forms of movement (called bulk push, vacuum pull, rotation, and exchange) are permitted. Incredulon allows even more special forms of movement, borrowed from Cylinder, Rampage, Dynamo, Restricted Rotation, Nuclear, and others.

Cr -- Movement of enemy and neutral units
  Cr1 -- Movement of enemy units
   In All-In C, a player may move a unit of either color on her turn. A pawn moves in the direction appropriate to its color, regardless of who moves it. Units may not capture units of the same color. The opposing (not the friendly) king may be placed in check by moving it or any other unit of either color. No move may reverse the opponent's previous move. [Note: I think this game is unplayable without a rule forbidding a player to move a unit which the opponent moved on her previous move -- otherwise an attack can be removed simply by moving the attacker to a square different from that from which it came.]
   In Avalanche C, each move consists of two parts: a legal move by one of your own units, followed by a mandatory one-square orthogonal advance of an opposing pawn (towards you) -- called a push. If every opposing pawn is blocked, no pawn push is made. Check may be given with either or both halves of your move, but must be removed with the first part of the move. En passant capture is illegal. The owner of a pawn chooses its promotion regardless of who moved it to the eighth rank. If every legal pawn push puts you in check, you lose ('self-mate'), even if you mated on the first part of your move! Avalanche has the unique minimal-length foolsmate 1 g4/e6 Qh4/f3# (note the notation of pawn pushes; a double slash indicates no push is available).
   Robin King has recently suggested Balanced Avalanche to reduce White's strong opening advantage -- White on her first move makes a standard move only, without pushing an opposing pawn.  In Double Avalanche, a player moves one pawn of each side forward after each move.
   March Hare C is a more general variant in which a player on his turn moves one of his own units, then an enemy unit. However, the type of enemy unit he can move depends on the type of friendly unit he moved. (In this paragraph, piece specifically excludes king as well as pawn). She may move a friendly pawn followed by any enemy unit, a friendly piece followed by an enemy pawn, or her king followed by an enemy piece or pawn. Check must be removed by a move of a friendly unit.
   In Gumption C, the players switch colors after every ten full moves (the player who makes the last move as Black makes the next move with the White units). The object is to mate the king currently controlled by the opposing player.
   Helpmate C is a balanced double-move variation. White moves a white unit on his first move; on each half-move thereafter, the moving player moves a black unit followed by a white unit. The player who mates either king first wins.
   Meddler's C is a strange variant of Ambi-Chess (Cx4); queenside units are moved only by the opponent.    Universion C is a co-chess (Cu1) in which co-squares are always active; a player may move enemy units on friendly co-squares as if they
were neutral (e.g. capturing enemy units with them).

  Cr2 -- Neutral units
   A neutral unit does not belong to either player; it can be moved by either player, who can capture enemy units (but not her own) with it. Neutral units check both kings. Neutral Conversion C is a co-chess (Cu1) in which enemy units on co-squares are converted to neutrals.
   In Neutral King C, there is only one king on the board, which can be moved as normal by either player (in place of a regular move). The king may never be moved to a square attacked by any unit of either color, nor may any move expose it indirectly to check from an enemy unit. When the king is not in check, each player may only move it orthogonally or diagonally toward his own end of the board (never forward or sideways). When it is in check, the player whose move it is must remove the enemy check; she may move the king in any direction, even to capture a friendly unit. She may also capture (or interpose against) the enemy unit giving check, even if this move puts the king into check from a friendly unit. The player mating the neutral king first wins (see also Ce, Cx5).
   One variety of neutral unit is a piece which imitates every move made by both players. A recent CV using this idea is Mimic C. The mimic starts at e3. As each player moves, the mimic simultaneously makes the same move (e.g. if White opens e4, the mimic moves to e5). The mimic captures any unit it lands on (even a friendly one), but cannot move through an occupied square or off the board (any move which would cause this is illegal). Castling does not move the mimic. Stalemate as well as checkmate wins. Ed Pegg gives the following 'foolstalemate' (the mimic's location at the end of each move is in parentheses -- captures denoted by asterisk): 1 Nf3(d5) e5(d3) 2 h3(d4) d5(d2) 3 Nfd2(b1*) wins.
   Another game of this type is Coin C. The coin is placed by Black at d4 or e4 to start the game. The coin can cross occupied squares without effect on the units there, but must land in an empty square. The coin imitates the king in castling. Stalemate is a draw. In Imitator C, neither queen can capture or be captured. Each acts like the coin in Coin C, but imitates moves by friendly units only. A queen can also be moved independently to facilitate future moves.

Cs -- Miscellaneous movement modifications
  Cs1 -- Modifications of earlier moves
   In Liars C, each player makes an orthodox move on his first turn. On each subsequent turn, a player may change one previous move, provided all subsequent moves by both sides are still legal. The game is usually quite short. Parallel Time-Stream C is a much more complex variant in which subsequent illegal moves are modified according to precise rules.
   In Retraction C, a player not in check may 'unmake' any conceivable previous move and make a new move in its place; this loosely resembles Marseillais C.

  Cs2 -- Hidden movement
   Kriegspiel (abbreviated hereafter KS) is the original form of a group of variants in which each player plays on his own board, without knowing the opponent's position. A third person (or computer program) is needed to referee, announcing illegal moves, captures and checks. This has long been a popular over-the-board variant (complete rules are in many of the references); it can also be played postally with a bit of effort.
    Nommenspiel is a KS variation in which the referee announces only when an illegal move has been made, and gives only the landing square of each move ("White has moved to c3"). Phil Cohen suggests that a player in check be notified secretly, to avoid time wasted on moves that do not remove check. Phantom C is a simplified version of KS, devised to be easier for a computer program to referee. Check is abolished; the object is to capture the opponent's king.
    Kriegspiel was invented to more closely simulate actual warfare, when the location of enemy forces is not precisely known. Some variants have been devised to give the players additional information. In Modern KS, each player asks the referee for the contents of seven squares before each turn; the referee tells him what enemy unit stands in each (or whether it is vacant). In Spy C, after a knight move, the referee tells the owning player the contents of every square adjacent to the knight's landing square. In Takeback KS, when a piece is moved to a square attacked by an enemy pawn, the referee announces it, and the moving player can retract the move if desired and play another.
   Kriegspiel Bughouse, invented at the New Cincinnati Chess Club, is played by four players, two against two. Each player can see his teammate's board but not the opponents'. The players move in rotation; passes are legal but the player who passed first must play after eight consecutive passes. Captured units are passed to the teammate as in Double Bughouse (Cy4). Splice C is a complex KS variant in which each player lists 100 or so moves before the game. These moves are then made in alternation, skipping impossible moves.
   Ghostrider C is a variant of orthodox chess in which knights are invisible and transparent to friendly units. A knight's location need only be revealed to the opponent when it captures, blocks an enemy unit trying to move, interposes against an enemy check, or is captured. Covert C is a commercial CV with partial hidden movement, using a computer program to referee. Units may disappear from the board and reappear later, one move away from the disappearance square.

  Cs3 -- Simultaneous movement
   In Synchronistic C, White and Black move simultaneously. This can be done by writing down moves, or with a referee as in Kriegspiel. Special rules deal with moves which interact with each other. If both moving units move to the same square, the White unit captures the Black if the landing square is in Black's half of the board, and vice versa. If both moving units try to capture each other, both are captured and removed from play. If one unit tries to capture the other, which is moving to a different square, the capture takes place only if the capturing unit ranks higher than its target (K ranks highest, followed by Q, R, B, N, P). Check and mate are as normal -- simultaneous checks (and even mates) are possible!

  Cs4 -- Rules changing periodically
   In Metamorphosis C, the rules change from one CV to another every full move (or every N full moves) in a fixed pattern (e.g. AAAABBBB...). Two or more different variants may be used. In Metamorphosis List C, the rules change every half move; a player makes a move under her current CV and then chooses a new CV for her next move; no variant may be repeated. A (large) list of allowed variants is recommended. See also Chess A vs. Chess B (Ca2).
Modification of Basic Capture Rules
   In the following sections, capture includes moves having effects on enemy units other than removal (see Cv). Changes in capture which result from changes in movement are covered in earlier sections.

Ct -- Modifications of the right to capture
  Ct1 -- Limitations of the right to capture
   In Must-Capture C, a player must make a capture when one is available, but has free choice of which capture to make. The object is mate (see also Parton's mock and compulsion chesses (Cx1)). In Mad-Cap C, captures are obligatory, and a capturing unit must continue to capture as long as it has additional captures available (it is not required to select captures so as to make the maximum possible number). The object is take-all; stalemating the opponent wins. In No-Capture C, captures are permitted only to mate or to relieve a check which would otherwise be mate. Perpetual check is not permitted; the game is nevertheless drawish. In Icelandic C, no guarded unit may be captured (optionally, units guarded only by a king may be captured). In Patrol C, only units guarded at the start of a turn can move so as to capture (and thus only they give check). In Recaptureless C, a capturing unit cannot be recaptured on the next half-move unless it gave check (this gives rise to situations similar to ko-fights in go -- see also Absorption (Cw1)). In Moss C, units move normally, but capture only with the power of the unit being captured. (E.g. WBb5, BPa6, BNc6 -- White can capture the Black pawn with her bishop, but not the Black knight (see also Strange Relay C in Cq1)). Pawns can capture in any direction, even backwards to the first rank. In Decimal Imitante Queen C, each side has two imitante queens (I in array) which move as queens but capture as in Moss C; they cannot capture enemy I's.

  Ct2 -- Extensions of the right to capture
   In Reform C, a player can capture his own units (this makes checkmate more difficult, as all squares adjacent to the king must be guarded) -- see also Bicapture C (Cx5). In En Passant C, e.p. capture is extended to all units; any unit which crosses an attacked square can be captured on the next half-move only as if it had stopped on that square (WRa1, BNb8, BBf8; after Ra8, Black may play Nxa6 or Bxa3, capturing the rook in either case). Knights cross the orthogonally adjacent square. In Blood Brother C, every piece (not pawns) is guarded by all friendly pieces of the same species (including promoted ones), and kings guard queens. When a piece is captured, any friendly piece of the same species (or K if Q is captured) can recapture on the following half-move (as in e.p.), regardless of its location (e.g. 1 e4 e5 2 Bb5 Nc6 3 Bxc6 N(g8)xc6). In Snowplow C, a Q/R/B may capture any number of enemy units along its normal line of attack, passing over any number of vacant squares (but blocked by friendly units or a board edge), ending on the square of the last unit captured. The enemy king is shielded by its units, and cannot be captured in a snowplow capture (1 a4 b5 2 axb5 Bb7 3 Rxa7,a8 (not check) Nf6 4 Rxb8,d8+).

Cu -- New methods of capture (non-replacement)
  Cu1 -- Coordination
   Ralph Betza conceived the idea of a family of games based on the coordinator from Ultima. These CV's, which use the same mechanism with widely varying effects, are collectively called co-chess. Each pair of identical pieces (not pawns) of the same color form co-pairs (queens co-pair with kings as well as other queens). Whenever one member of a co-pair moves to a square on a different rank and file from the other member, two co-squares are created, each on the same file as one piece and the same rank as the other. For example, if the king is at e1 and the queen moves to d3, co-squares are formed at e3 and d1. Castling allows  the  possible  formation of both king/queen and rook/rook co-squares. Promoted pieces allow multiple pairs; a moving piece forms co-squares with every piece it can co-pair with, but co-squares are not created on the turn a pawn promotes. Any unit standing on a co-square when it is formed undergoes a mandatory co-effect, which depends on the variant. Co-effects usually apply to enemy units only, but see [201, 434, 628]. Co-squares have no effect after the half-move in which they are created (except in [140, 652]); moving a piece to a co-square created on a previous move has no effect. No further co-squares are created as a result of the co-effect (except in [469]). It is legal to move into check (even castling into or through check) if the check is immediately removed as a result of a co-effect (called co-removed check).
   The three most successful co-chesses are Conversion C (Cv1), Transportation C (Cv2), and Overloader/Restorer (O/R) C (Cw1). These and other co-chesses are listed in the Index under Co-Chess, and described in the Panorama based on their effects. The simplest form is Co-Capture C, in which enemy units on co-squares are simply removed from play (friendly units are unaffected). A threat to remove the enemy king is check; orthodox captures and checks are also allowed (Cohen has suggested a variant in which orthodox replacement capture is allowed by pawns only (see also Conversion)). Reversion is a variation of co-chess (it has been specifically combined with Conversion, but should work with other co-chesses) -- two unpaired pieces immediately form a new co-pair (i.e. if a player loses a rook and a knight, her remaining rook and knight are now a pair). If either piece regains a natural partner by re-conversion or promotion, the unlike co-pair is dissolved and the natural co-pair is reformed. If a player has three unpaired pieces, he must choose two to form a co-pair.
   In Coordinator C, the Coordinator (C in the array) is exactly as in Ultima, moving as a queen, forming co-pairs with the king, and capturing as in Co-Capture C.

  Cu2 -- Rifle
   In Rifle C, all captures are made from a distance -- a unit which could make a normal replacement capture of an enemy unit simply removes it without moving. One form is played with all captures optional, another form (recently dubbed Shoot C) is played with captures obligatory (see sample game 10). Rifle C has also been combined with Scottish [543]. Missile C (another variety of Exotic C (see Cq5)) is a form of Rifle C in which each unit can make only one Rifle capture per game. Units are allowed to make replacement captures freely. A variation gives each unit a shield (protecting it from one Missile attack) in addition to its missile. The Prussian National Game is a 19th-century modification of [251] in which each side has two pieces (batteries) which moves as queens (up to three squares) and capture by Rifle (both on the same turn if desired). Lazer C is a commercial CV using a form of Rifle capture borrowed from wargames.
   In Machine Gun C, after a unit moves, it simultaneously captures and removes every unit it attacks, being removed itself (ending the turn) if any of those units attack it in return (called crossfire). Units behind other attacked units along R/B/Q lines are shielded and are not captured. The object is take-all. In Automatic Rifle C, a unit, instead of moving, may capture every unit it attacks, in any order desired. The firing unit may stop at any time; crossfire removes the capturing unit and ends the turn. Unlike Machine Gun C, units exposed to attack by the removal of other units can also be captured, as in Snowplow C (Ct2). Pawns, kings, and knights can capture multiple units in an unbroken straight line. Orthodox chess moves and captures may be played at any time; Rifle captures are not obligatory. The first capture of a game must be by replacement ('truce'); thereafter, autorifle captures are permitted.

  Cu3 -- Custodian
   Scaci Partonici is a group of variants in which one or more enemy units in a straight line (diagonal or orthogonal) can be taken by custodian capture (e.g. with a friendly unit at a5 and enemies at b5/c5/d5, a friendly unit moving to e5 takes all three; Parton calls this a line partonic take). Two enemy units can also be taken by reverse custodian capture (e.g. with enemy units at a5 and c7, a friendly unit moving to b6 captures both (contrary partonic take)); with enemy units at c4 and g4, friendly units at d4 and e4, a friendly unit moving to f4 takes c4 and g4). These captures can be combined (with enemy units at c7/d5/d6/g5, and friendly units at b8/f5/g3, the move g3e5 captures all four enemy units; with enemy units at a4/c4/d4 and friendly units at b2/e4, b2b4 takes all three enemy units (mixed partonic take)). Capture by replacement is prohibited; partonic capture is always optional. Units must make forward moves only (advancing at least one rank) until they reach the last rank -- pieces then gain their full movement and pawns promote to any piece (Parton advises using larger pieces for those which can move in any direction) -- see Advancing Duffery (Cx6). The object in standard Scaci Partonici is take-all (in Royal Scaci Partonici, the object is to capture the enemy king -- Partonic C is an alternate array).  Decimal Scaci Partonici (see [182] for three possible arrays) can be played as take-all or Royal.
   In Chessenat, each side adds eight wazirs ('kelbs') on the third rank, which capture by orthogonal custodian capture; other units are orthodox. In Custodian C, all units can capture by replacement or orthogonal custodian capture (or both simultaneously). Pawns may make custodian capture after their normal diagonal move or single or doublestep forward. The enemy king cannot be captured, but can be mated or surrounded on all four sides to win.

  Cu4 -- Capricorn (Butter)
   Capricorn is a form of capture invented by V.R. Parton in which the capturing unit moves to a square adjacent (orthogonally or diagonally) to one or more enemy units, 'butting' them off the board. Up to seven units (eight for unorthodox leapers) may thus be captured in one move. In Butter C, all units capture only by Capricorn -- it is illegal to move to an occupied square (Parton is not specific, but presumably pawns can only move diagonally in order to capture, and cannot capture after an orthogonal move). The object is to capture the enemy king -- check is abolished. In Mock Butter C, the object is to take all enemy units (the king is a normal unit). There is also a 10x10 form of Mock Butter C called Best Decimal Butter. Decimal Butter is also played like Mock Butter, with a choice of arrays from four different variants (see [177]). A more limited form of Butter C is Capricorn C, in which rooks (including promoted ones) capture by Capricorn and other units capture normally. The object is checkmate. A rook can capture an enemy unit even if it starts its move adjacent to it (e.g. WRe4, BNe5, White can play Rd4(xe5) or Rf4(xe5)). Alternately, knight (or even bishop or queen) can be given Capricorn power instead of rook.

  Cu5 -- Dynamo (pushing and pulling)
   In Dynamo C, every piece has the power to push or pull one unit (per turn) of either color within its normal range. No unit can pass through or stop in an occupied square, whether being pushed/pulled or moving under its own power. A rook, bishop, or queen can push or pull another unit along normal attack lines any number of squares toward or away from itself. The pushing/pulling unit may stand still or follow (when pushing) or lead (when pulling), moving any distance in the same direction; neither unit may pass the other. A unit of either color may be pushed off the edge of the board; the pushing unit may also move off the board if desired. A unit of either color may be pulled off the edge of the board; the pulling unit must also leave the board in this case. A piece may also leave the board without pushing or pulling. There is no orthodox (replacement) capture; all units leaving the board are removed from play (E is given as their destination).   A king or knight can also push or pull a unit it attacks/guards. To push, the K/N moves to the square of the unit being pushed, which makes a further move of equal length in the same direction (the same push can be made without moving; e.g. Ng1e2(e2c3) or Ng1(e2c3)). To pull, the king or knight moves directly away from the pulled unit, which moves to occupy the K/N's starting square. The king or knight may push a unit off the edge (but cannot follow off the edge) -- neither can capture by pulling. The knight can go over the edge while pulling a unit within range. Kings may never go over the edge under their own power. Knights and units they push/pull can leap occupied squares as usual.   Pawns can push only -- a friendly unit one square straight forward or an enemy unit one square diagonally forward, remaining in place or entering the pushed unit's starting square (which must be a square the pawn could normally move to). A pawn on its 2nd rank can push a friendly man (on the same file, third or fourth rank) one or two squares forward, following one or two squares if desired. A Pawn may be pushed/pulled to its 1st rank, from which it may only make single steps/pushes. A pawn pushed/pulled to its 8th rank promotes to a piece selected by the player who pushed/pulled it there (the opponent may not check himself thereby).    Normal moves without pushing/pulling are permitted at any time; castling must be a normal move and obey the usual restrictions. A king or rook on its original square can castle if it has not moved under its own power. Check is a threat to push/pull the enemy king off the board; the object is checkmate. NOST added several rules: en passant is abolished; kings may not be pushed or pulled through check (i.e., they may not cross squares from which the opponent could push or pull them off the board); no move may restore the position before the opponent's previous move. The shortest foolsmate is 1 Ng1e2(Pc3) Qd8b6(Pa5) 2 f2f3 Qb6f2(Pe3)# (the Pe3 prevents the escape move Ke2(Ne3)). This is a very complex game; see sample game 2 for examples of the moves. A more playable form is Doublemove Dynamo, which combines Dynamo with Doublemove C (balanced move pattern, object to capture the enemy king, Doublemove rules for stalemate, moves which do not change the position forbidden).
   Push C is the variant from which Dynamo derived. In Push C, units may push as in Dynamo, but must follow along one square behind (thus a unit pushing another off the board ends its own move on an edge square). The destination of a pushed unit is not given -- it is determined from the moving unit's destination. A foolsmate: 1 Ra1a5 Ke8e7 2 Ke1e2 Qd8g53 Qd1f3#. In Tank C, the knight ('tank') moves as a counselor (no-royal king). It can capture an adjacent enemy unit or push an adjacent friendly unit to the next square along the same line (following as in Push C). The pushed unit may in turn push another friendly unit or capture an enemy unit, etc. (details in GFC).

  Cu6 -- Miscellaneous methods
   In Spite C, replacement captures are not allowed; units can only move to vacant squares. A moving unit captures any enemy units attacking its landing square (even those which already attacked its starting square) -- see also Moss C (Ct1). Screened units are not captured. A pawn doublestep captures enemy pawns on either side of it (e.p.). Check is ignored; the object is to capture the enemy king by moving a friendly unit to a square adjacent to it. A variant is Spite Chess Plus Chess, in which both Spite capture and replacement capture are allowed, and the object is checkmate. One of numerous foolsmates is 1 c3 Nf6 2 g3 Ne4#.
   In Cassandra C, each player openly predicts, after every move, the location of an enemy unit (even the king) a fixed number (usually 4-8) of turns in the future, removing it if the prediction is correct. Mate or removal of the enemy king wins. In Plague C, moving units cause 'plague' which kills units moving to affected squares (NA213 describes three variants). In All Mate C, units are captured by attacking them so they have no escape squares. 'Mated' units may be removed in any order, possibly exposing others to 'mate'. In Archimedes C (based on the board game of the same name), units are captured by being attacked by two units simultaneously. Dekle has devised decimal variants using four Ultima pieces: Coordinator (Cu1), Immobilizer (Cv3), Longleaper (Cg4), and Withdrawer -- the latter uses two Ultima withdrawers, which capture using the method borrowed from fanorona.

  Cu7 -- Mixed capturing methods
   Ultima, described by Paul Yearout in WGR5 through 7, is the best-known variant using mixed capturing methods (K -- replacement, Q -- withdrawing, N -- longleaping, R -- immobilization and coordination, B -- imitative, P -- custodian).  Ultima has given rise to other variants, including Abbott's 1968 limited range variant (see WGR8), which appears in the paperback edition but is not part of the standard NOST rules. See also Co-chess (Cu1) for a family of games based on the coordinator.
   In Ulti-matem, each pawn (represented by a miniature piece) moves as the piece which would stand in its starting file in orthochess (the e (king) pawn makes a double knight move in any combination of directions), capturing by orthogonal custodian as in standard Ultima. Unorthodox Ultima adds two new pieces, the Neutralizer (which temporarily removes the capturing power of an enemy unit) and Repeller (which pushes an enemy unit away from it in a manner somewhat similar to Dynamo). Unfamiliar Ultima is an unpublished variant, probably the most complex CV ever invented. Each side has eight new pieces in addition to its pawns. Each piece has a different effect; there are rules defining the interaction of each pair of pieces.
   An interesting but untested variant is Bogart's Ultima. Two new pieces are added to standard Ultima. The Golem (G) moves one or two squares as a queen, capturing by replacement. In order to remove it from play, it must be captured twice (not necessarily on consecutive turns). Clearly the enemy king cannot make the first capture. A replacement capture by an enemy golem or chameleon, however, counts as two captures and removes it at once. The chameleon can only move one or two squares to capture a golem. A once-captured golem is signified by G'. The Absorber (A) starts as an Ultima pawn (rook move, orthogonal custodian capture). When it captures an enemy piece (except a chameleon), it adds that piece's capturing power as in Absorption C. If it captures the enemy absorber, it adds any powers the enemy A has gained. It gains a queen's move when it captures any piece with queen movement. An absorber must make both captures of an enemy golem (or an enemy A that has absorbed golem power) in order to gain golem power -- if it does so it must be captured twice, but can move up to three spaces a turn. A chameleon can capture an absorber using any power the absorber has gained.
   Parton devised a decimal CV called 2000 A.D. which uses pieces he invented for his other variants (the Ximaera as in Chimearine C; the Gorgon as in Demigorgons, but with power to capture by replacement also; the Capricorn as in Butters, etc.) in a complex game similar to Ultima.  The object is to capture the enemy Empress (royal queen). Most pieces move as queens but have different capturing powers; there is a Mimotaur which uses imitative capture as the Ultima chameleon. A wilder version, Royal Fury, uses a piece combining the powers of all pieces (cf. [366]) as the royal piece for each side.
   Two of the pieces in Super C use unorthodox captures: the Cyclops similar to pieces in Snowplow (Ct2) -- also a directional piece as in Ploy (Cg5), and the Archer as in Rifle (Cu2). It also uses 'super pawns' similar to those in Chess II (Cf1) -- they may make a doublestep move (leaping if desired) only from their initial rank, but retain doublestep capture (still leaping) anywhere on the board.

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Oxymoronic CV's: Spherical Dynamo, Kamikaze Absorption, Mobius Billiards
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Cv -- Disposition of captives (captured unit not removed from play)
  Cv1 -- Conversion
   In conversion chesses, captured enemy units are not removed from play, but instead become friendly units of the same species. The best known form of this is Chessgi, a popular variant derived from the Japanese game of shogi. A converted unit belongs to the captor, who can re-enter it on a vacant square on any later move, instead of moving a unit already on the board. The set of captured units is called the reserve, and the placing of a unit from the reserve instead of moving is called a drop. A pawn may not be dropped on its eighth rank. A pawn placed on its first rank can singlestep or capture normally. Any pawn on its second rank can doublestep. A rook dropped at a/h-1/8 can castle. Pawns promote normally, and retain their rank when captured.
   Several other versions of this idea differ mainly in restrictions on drops. In Neo-Chess (independently invented by Randolph in 1972), pawns promote by being exchanged for pieces from the opponent's reserve (a pawn moved to the eighth rank when the opponent has no pieces in reserve is immobile for the rest of the game); no unit may be dropped on the eighth rank (the last rule was dropped in a later version called Mad Mate). The commercial sets for Randolph's Neo-Chess/Mad Mate have round, double-sided pieces (with orthodox symbols) which are flipped over (as in reversi) to show the capturing player's color (shogi pieces are uncolored pentagons which point in the direction of the opponent to show which player they belong to. Dekle's Chessgi improves defense in standard chessgi by prohibiting all drops giving check (or alternatively using dragon horses instead of bishops -- adding the wazir move to their normal power); pawns promote only to counselors (non-royal kings, useful for defense) and revert to pawns when captured (see also [232, 340]). Robert Bruce earlier proposed a game [121] with restrictions similar to shogi -- pawns cannot be dropped to give mate, pawns cannot be dropped on their eighth rank, and promoted pieces revert to pawns when captured. Chessgi has also been combined with Scottish C [538]. Tandem C is a chessgi variant which resembles Double Bughouse (Cy4), but needs only a single set and two players.
   Two variants, using chips to 'pay' for reentered units, have been devised to allow players more options in managing reserves and planning attacks. In Token C, the capturing player receives chips (according to the usual values P=1, N/B=3, R=5, Q=9) for capturing a unit. At the start of any future turn a player holding chips may trade the corresponding number of chips for a unit of his choice (it need not be one captured earlier). The player then takes his usual turn, either reentering a unit as in chessgi (but not the one he just 'bought') or moving a unit already on the board. In Bankhouse C, each player starts the game with 25 tokens. Captured units join the captor's force as usual; a player may reenter a unit on a vacant corresponding first rank square (e.g. White may enter a converted knight at b1 or g1) by paying the opponent the required number of chips (values as above). In addition, a player may ransom a lost unit (from the opponent's reserve to his own) at the same cost, paying a second time when he re-enters it. Any number of units may be ransomed on one turn, but at most one may be re-entered on the same turn. 
   Conversion C is a co-chess (Cu1) in which enemy units on co-squares are converted to friendly units of the same type; friendly units are unaffected (but see [201]). A threat to convert the enemy king is check, analogous to ordinary check. Orthodox captures and checks are also permitted. Cohen suggests that orthodox (replacement) capture be allowed by pawns only (see also Co-Capture).
   The idea of conversion might be combined with other variants, especially those using non-replacement capture. It is possible, for example, to imagine Rifle Conversion, in which units 'shot' by rifle capture become friendly units (in order to make this playable, a player may not reconvert a unit which her opponent converted on the previous half-move). Similar to this is Turncoat C, in which any friendly unit attacked by the opponent at the start and end of a turn changes (at the end of that turn) into an enemy unit (e.g. 1 e4 e5 2 Qh5 g6 (Black pawn at h7 becomes White)).
   When ordinary replacement capture is used, however, the capture square is occupied by the captor, and something must be done with the converted unit (multiple occupancy is possible, but the same rule as above, forbidding immediate recaptures on the same square, is needed). In two variants described in JENO, the converted unit is immediately moved elsewhere. We will use the name Conversion Circe for Tressau's variant, in which the converted unit is placed on the appropriate starting square if vacant (as in the problem Circe convention in Cv2). Boyer proposed a variant in which the captor immediately relocates the converted unit to any vacant square (bishop on the same color it was captured on; pawns not on the eighth rank); we will call this Conversion Bughouse.

  Cv2 -- Repositioning
   One group of variants involve captured units being moved to a different square on the board instead of being removed from play. The best known of these is Bughouse C -- when a unit is captured, its captor places it on any other vacant square on the board. Bishops must remain on squares of their original color; pawns cannot go to their first rank (a version called Putback C has neither restriction; pawns on the first rank can triplestep with e.p.).
   Quite different from Bughouse are Circe C and its variants, which were originally devised for problems. In Circe, when a unit is captured, it returns to its starting square. A promoted pawn which is captured reverts to a pawn and returns to the second rank of its original file. In Circe and its variants, a unit is removed from play only if the designated relocation square is occupied. In Circe problems, since there is no game history, there is a convention that pieces return to starting squares of the same color as the one they were captured on, and pawns to the second rank of the file they were captured on -- but this convention is NOT followed in play (it is followed in Circe Malefique, in which captured units are moved to the starting square of the corresponding enemy unit -- e.g. a white pawn captured at d4 moves to d7, a black knight captured at d7 moves to b1).
   In Antipodean C, a captured unit is moved to the square 4 squares diagonally away (there is only one such square for each square of the 8x8 board). Symmetric Circe and Mirror Circe similarly replace captured units on the square exactly opposite the capture square (reflected through the center point and the line dividing between ranks 4 and 5 respectively). A unit captured on f7 is replaced on c2 in Symmetric Circe and f2 in Mirror Circe. Circe effects do not apply to kings, and check and mate are as usual, except in the variant called Total Circe (in which kings may be captured and replaced; a king is in check only when it (or another unit) occupies its starting square). The variant Progressive Circe has become popular in AISE (combining Italian Progressive rules with standard Circe), and was played in the First Heterochess Olympics; see sample game 7.  Giveaway Circe is also played.  See also Reincarnation Circe and Chameleon Circe (Cv4).
   Transportation C is a form of co-chess (see Cu1) in which any unit (except a king) on a co-square is transported -- moved, by the player whose move created the co-squares, to any other vacant square on the board, including the square just vacated by the moving piece. All transportations are simultaneous, so a unit on one co-square can be transported to another (exchanges are also possible). Pawns cannot transport to their eighth rank. Pawns transported to their first rank can singlestep or capture normally. Pawns on their second rank always have a doublestep option. A rook which is transported away from its original square and later back to either rook square retains the right to castle if it has not moved under its own power. Betza found 295 Transchess foolsmates with White mating on his second move. (One example is 1 b3 d5 2 Bb2(f2d7,Nf6)# ). Columbia Cannon Transchess (Cg3) has 159 one-move foolsmates; e.g. 1 Bf4 Bb4(Nc1)#. In Polyactive Transchess, transported pieces can form new co-squares, in turn causing more transportations (Cohen thinks this, as well as Putback Transchess (above), are unplayable). Suction C is the opposite of Transportation -- any unit except a king may be 'pulled' to a co-square (even a pawn to an eighth rank square, where it promotes immediately). In Autosuction C, only friendly units may be pulled to co-squares.   
  Another Parton game with an unorthodox form of 'capture' is Chimaera C. The chimaera is an uncapturable piece which moves as a queen -- it can exchange places with any enemy unit by moving to its square (i.e., the unit must be a queen's move away with no units intervening). If a chimaera changes places with an enemy chimaera, the opponent cannot reverse the move immediately -- she must make another move first (analogous to the ko-rule in go). The standard game is decimal; Cohen has suggested an 8x8 array. A variant, Chimaerine C, uses chimaerines (which can be captured) instead of chimaeras.
 
  Cv3 -- Immobilization
   In Demigorgons (and its decimal version Gorgona C), the demigorgon (so-called since its 'petrifying' effect is only temporary) is a long-range version of the Ultima immobilizer -- it moves as a queen, but cannot capture. Instead it immobilizes any enemy units whose squares it could move to; no unit may move, capture, or check while it is a queen's move away from an enemy gorgona. A gorgona can immobilize the enemy king; this does not win, but a check from another friendly unit which cannot be captured or interposed is mate. Gorgonas of opposite colors can mutually immobilize each other; they can still immobilize other units, since they immobilize by 'looking', not by moving. Only a knight can capture a gorgona. See also 2000 A.D. (Cu7). Co-Immobilization C is a form of co-chess in which co-squares are always active -- units on co-squares cannot move.  Immobilizer C uses two Ultima immobilizers.
 
  Cv4 -- Demotion
   Parton claimed that a game of standard Bughouse between good players could go on indefinitely, so he proposed a variation (we call it Demotion Bughouse) in which captured pawns were removed and captured pieces were reduced one step in value (Q => R => B => N => P) before being repositioned as usual.  Demotion C is a co-chess (Cu1) in which enemy units (except kings) on co-squares are reduced one step in value (pawns are removed) by the same reduction scheme (remaining where they are). In Reincarnation Circe, captured units are modified one step according to the cycle K => Q => R => B => N => P => K and then replaced (as in problem Circe) on the appropriate starting square. The object is to capture all but the last remaining enemy king, then mate it (see Cx3).
Chameleon Circe uses a different cycle in the opposite direction (N => B => R => Q => N) to alter captured pieces (pawns are removed; kings cannot be captured). Nearly any variation using conversion (Cv1) can be changed to use demotion instead.

Cw -- Side effects of capture
  Cw1 -- Effects on the capturing unit
   Several variants use the idea of a capturing unit taking on the power of the captured unit, either in addition to its own power or instead of its own power. Capturing a black pawn causes a white unit to become a white pawn, or add a white pawn's power to its own). In all variants (excpet Biflux) where the king can add other powers by capture, kings moving as Q/R/B cannot cross an attacked square except to capture an opposing king which does not check it in return.    In Absorption C, any capturing unit adds the power(s) of the captured unit to its own (we call this process absorption in all related variants). Units gaining pawn power may: (1) capture opposing pawns en passant; (2) doublestep from the second rank (they are subject to e.p. capture unless they also have rook or queen power); (3) promote the pawn component (if desired) to any piece by a normal pawn move to the eighth rank. Because it is a disadvantage to capture a guarded unit (the opponent gains by recapturing), Absorption C works better in doublemove or progressive form. AISE plays a variant called Cannibal C, combining Italian Progressive with Absorption. Players who prefer single move variants might try Recaptureless Absorption (see Ct1).
   Escalation is a complex form of Absorption C in which each side starts with an army of the five simplest leapers (F/W/A/D/N). Units add to their own powers by capturing as in Absorption. A unit composed of one or more leaper powers only promotes to the corresponding riders upon reaching the opposing 8th rank. Detailed rules in GPJ7.
   Biflux C is one of the wildest forms of co-chess -- the pieces of a co-pair gain the powers (as in Absorption C) of any enemy units on their co-squares -- the enemy units are unaffected. Any pieces gaining enemy king power become royal, and must be defended from check (as in Co-Regal). Royal pieces with B/R/Q power may cross attacked squares, and check opposing kings even if the latter are guarded. A unit having combined powers may move to a square with the power of any or all of its components having that move, forming co-squares with any corresponding friendly pieces. E.g., a R+Q+P on d4 may move to d5 as R (co-pairing with all friendly units having R-power) and/or Q (co-pairing with all friendly units having K or Q power) and/or P (forming no (extra) co-pairs). A unit on its seventh rank having pawn power may promote its pawn component by making a pawn move to the eighth rank.
   In Frankfurt C, a capturing unit takes the power of the captured unit in place of its own (a white knight capturing a black bishop becomes a white bishop -- we call this mutation). Kings, however, keep their own power and add the power of the captured unit (the rule above against crossing attacked squares applies).  Pawns promote normally unless capturing, in which case they promote to the piece captured. In Kaleidoscopic C, a capturing unit (except a pawn or king) may mutate as in Frankfurt if desired, or remain normal. Mutation C, invented for the First Heterochess Olympics (see sample game 7),  combines Italian progressive chess with Frankfurt. Kings remain normal after capturing. Queens may not check kings; any move which exposes either king to check from the opposing queen is illegal.
   O/R Chess is a co-chess (Cu1) in which any enemy unit on a co-square is overloaded, losing all powers except ordinary movement. An overloaded unit cannot capture, check, castle, or act as part of a co-pair. An overloaded pawn in addition cannot promote or doublestep. A friendly unit on a co-square is unaffected unless it is overloaded, in which case it is restored, regaining all of its former powers. The effects of overloading last until/unless the affected unit is restored. An overloaded pawn can move to the eighth rank, but remains immobile until restored, at which time it promotes immediately. Overloading the enemy king does not win; it must still be checkmated, but a friendly king may check (and mate) an overloaded enemy king!
   Nuisance C is a co-chess in which nulls (see Cw2) are created on any empty co-squares, and removed when already present on co-squares. This may be played alone or combined with other co-chesses. See also Double Conversion C (Cw2).
   In Kamikaze C, capturing units are removed from play along with their captives. In the original form, kings are immune to Kamikaze effects, check is ignored, and the object is to promote a pawn (Cx6). A more chesslike form is Total Kamikaze, in which check is normal, and the object is checkmate (thus kings cannot capture, and any check forcing the opposing king to capture wins); AISE has found this quite playable as a progressive variant.
   Reaction C is a complex set of twelve variants in which either the captor or captive unit moves away from a capture square under the power of either unit. See Chessics for details.
 
  Cw2 -- Other side effects of capture
   In Zombie C and its relatives, when a capture square is vacated, a new unit (called a zombie) is created on that square. This unit is of the same species as the last unit captured there and the color of the last captor. If a white bishop captures a black knight at c6, then moves away, a white zombie knight (notation ZN) is created at c6. If a series of captures and recaptures takes place on the same square, only the last capture before a unit leaves the square produces a zombie. Zombie units cannot pass through or stop in squares containing regular units, and vice versa. Zombie pawns promote to any desired zombie piece, and retain their promoted power when captured. Zombie pawns on their second rank can doublestep. When a zombie captures an enemy zombie, a double zombie (which blocks both zombies and regular units and vice versa) is generated as above. Double zombies produce triple zombies, etc.
   Two more playable variations are Dying Zombie C, in which zombies capturing zombies produce nothing, and Reincarnation C (the best of the family), in which zombies capturing zombies produce regular units. A rook captured and reincarnated on its original square can castle. The original game of this family,  Null C,  produced nulls (immobile uncapturable blocks) after captures; this proved too drawish.
   A quite different game is Ghost C, in which captures produce ghost units, belonging to the player captured (White B x Black N produces a Black ghost knight). Ghost units have the powers of normal units, but cannot be captured a second time. Recaptures do not erase ghost units; each capture creates a ghost, stacked on the square in reverse order. When a ghost unit leaves a square on which it captured and was recaptured, the previous ghost is freed.  In Shazzan!, when a unit is captured, any enemy units which it captured previously are returned to their capture squares (if vacant).
   Double Conversion C is a variant of Conversion (Cv1) in which friendly units on co-squares are also converted to enemy units!  Double Reversion Conversion (Recon2) combines this with Reversion (Cu1).

Cx -- Modifications of objective (check and checkmate)
  Cx1 -- Capture of all of opposing units
   The term take-all refers to variants in which the objective is to capture all of the enemy units. The king is a normal piece; castling is prohibited and check is ignored. See sample game 8 for the AISE progressive version. Parton suggested that many of his variants could be played with objectives other than checkmate. His term for games where capture is obligatory is mock (or scacia) when the objective is take-all, compulsion when the objective is to take the enemy king. In his simple variant Mock C, pawns on their second ranks must capture or doublestep on their first move.
   In Robado C, a win can be achieved (in addition to checkmate) by capturing all of the enemy units except the king, providing that the enemy king cannot capture the only remaining friendly unit on his next move -- this rule was customary in Shatranj (Cc1). Schmittberger has suggested (Games 54 (G84)p53; Chess Life 42:5 (Y87) p49) that draws could be reduced by allowing wins by robado as well as stalemating the opponent -- both of these changes would drastically alter endgame play. Another method of reducing draws is to prohibit perpetual checks as well as any other repetition of position.
 
  Cx2 -- Loss of all of own units
   Giveaway (Losing) C is a popular and longstanding variant. In the standard form of the game (as played in NOST and given in several other references), the king is non-royal and may be captured as any other unit -- check and castling are abolished. Pawns may promote to king as well as any other piece; e.p. is normal. Captures are obligatory -- if a player has a choice of captures, she may take any one. The first player to have no legal moves (either by losing all of her own units, including the king, or by being stalemated) wins. It is known that the opening move 1 d3 loses; the main line of analysis is given in NCH.    Under AISE/1HO rules, however, stalemate is a draw (also cited in about half the references). If five moves by each player pass without a capture or pawn move, either player may claim a draw unless one player can demonstrate a forced win. In another variant, pawns automatically promote to queens. Take Me is an early form of Giveaway in which capture of a specific enemy unit is obligatory when the opponent demands it. Pawns promote to a lost piece of the owner's choice. In a different form of the game (which might be called Giveaway Robado), checks are normal, the king cannot be captured, and the object is to be mated or lose all of your units except the king. Giveaway is popular in combination variants [see 234, 257, 329, 474 (Italian), 644; also combined with 53, 370, 516].

  Cx3 -- Multiple targets
   In multiple target variants, the objective is capture of all units of a specific type -- these may still be called royal, although they may be freely put en prise. Most two-Rettah versions of Rettah C (Ce) are of this type, but see Double Rettah below. In Kinglet C, the king is a normal piece and check is ignored. Pawns (called kinglets) move and capture normally, and may promote to any piece, including (non-royal) king. The objective is to capture all of the opponent's remaining unpromoted pawns. All pawns may be put en prise, even the last; a player loses if she promotes her last remaining pawn or places it en prise. A draw by stalemate occurs when a player has only blocked pawns remaining. The variant Scottish Kinglet, played at NV'84, combines Kinglet with Scottish C, with the added rule that a series ends when a pawn is captured.
   Extinction C is a extension of the ideas of Kinglet and Co-Regal (see below). The object is to capture every one of any species of opposing unit; i.e., one can win by capturing the opponent's king; queen; both bishops; both knights; both rooks; or all eight pawns. A relict unit is the last of its species (the king and queen are relict at the start). Pawns promote to any piece, including king. Promotion can extend the life of a relict species, as promoted pieces count as part of their species (if a pawn promotes to queen, the opponent must capture both queens to win). Promoting one's last pawn loses. Any unit (relict or not) may be placed en prise (e.g. a king can capture a protected unit), though placing a relict piece en prise obviously loses unless it wins by capturing a relict unit itself.   Castling is allowed whenever the king and rook have not moved and the intervening squares are vacant: either or both pieces can castle from, across, or onto attacked squares.  See sample game 3.
   A variation of multiple target games is one in which all but the last royal unit must be captured, and the last then mated. Any royal unit may be put en prise as long as it is not the last one remaining. A simple example is Hydra C, in which pawns may promote to king (see also Cv4). Royal Pretender C is a relative of Kinglet C (pawns are called Royal Pretenders), but if a player's last pawn promotes, the species it promotes to becomes the opponent's new target. E.g. if White's last remaining pawn promotes to rook, Black must capture all of White's rooks to win. Unlike Kinglet, the last pawn (or other species if the last pawn promotes) cannot be placed en prise.
   Double-King C is a variant invented by Moeser which has undergone several modifications. The latest version is played on an 8x8 board, with four extra squares at de09 on which the two kings for each side stand behind their armies. The piece at e1/e8 is a squirk (squirrel plus rook). The object is to capture one enemy king and then mate the other. The earlier forms of the game were played on a 10x8 board, with a squirrel (later squirk) and an extra king on each side.
 
  Cx4 -- Multirex
   In multirex variations, each player has two or more royal units, none of which may be left en prise. A player is checkmated when any of his royal units are in check, and any move he makes will still leave at least one royal unit in check. One way of mating is a fork or skewer of royal units by an uncapturable or guarded unit.    Several of the best-known multirex CV's were invented by Parton. In Co-Regal C, both the king and queen are royal and subject to check. Queens may not castle. Queens may cross attacked squares, but may not move into check (thus a queen cannot attack another queen, and can only attack a king from a distance). Pawns may still promote to queen (not king), but promoted queens are also royal. See also [153, 539]. Double Rettah C is a version of Rettah C (see Ce) using two Rettahs per side. Unlike other versions, the object is to checkmate either or both opposing Rettahs as defined here -- in this variant, a player is not obliged to capture a unit attacking one of his Rettahs. Chess Tweedle is one of Parton's decimal forms of two-king chess. Ambi-Chess is a doublemove form of Chess Tweedle. Each player has two armies (the queenside units must be distinguished from the kingside units; all units may roam the board freely). On each move a player must move one unit from each army (left army first, then right). A stalemated army passes its half of the turn. Alliance C is a variant of Ambi-Chess.
   Incognito C is a variant of Co-Regal. Each player secretly chooses a piece in addition to the king to be royal (the choice should be written down, or sent to a neutral party in a postal game). Checks to royalty must be removed, though the opponent is not informed when he attacks the secret royalty. Checkmate is as in Co-Regal. In another version, both players must secretly select a pawn as a third royal unit; the selected pawn cannot promote.
   A few two-king variants are actually four-handed games adapted to two players by having each player control two armies. In Howard's Double C, players control adjacent armies on a standard four-winged board, using a balanced doublemove start. Hayward's Double C is played in singlemove on a 16x12 board.

  Cx5 -- (Modified) check
   Many of the oldest variations involve various prohibitions or obligations involving check or capture. In Checkless C, check may only be given when it is mate; this allows mates similar to progressive mates in Italian Progressive, but the rules contain a paradox, exposed in an ingenious 1969 problem by Gerd Rinder from Die Schwalbe (3R3R/3K4/8/4k3/8/2n2n2/8/B6B; N = nightrider). Rh8e8 appears at first to be mate, but the reply Kd5 is also mate, except that it can be answered by Ke7, etc. his endless cycle can be eliminated by a rule that a check is mate (and therefore legal) if the only parrying move is a check.  A more restrictive version, Absolute Checkless C, forbids any unit to cross a square from which it would give check. In Check Force, a player giving check determines how the opponent removes check (I assume this means by specifying interpose/capture/move king, not the exact move -- the choice given must be possible). In Patzer C, check must be given whenever possible. A player wins by giving ten consecutive checks ('decimating') or by checkmate.
   In 1916, Frank Hopkins proposed a new variant, Single Check C, in which the object is to be the first player to give check. Frank Marshall, however, found a forced win for White using only his two knights. One way is 1 Nc3 e6 (1...d5 2 Nb5 Kd7 3 Nf3) 2 Ne4 Ke7 3 Nf3, winning with the threat of either 4 Ne5 or 4 Nh4. 1...e5 and 1...d6 are met by 2 Nd5, while 1...f6 or 1...f5 are met by 2 Nb5. This is of practical use in Bank of Scotland (Cn3). Hopkins then devised a new version in which the pawns for both sides start on their third rank instead of their second. Another version called Presto C has been suggested -- pawns start as normal, and the first player to give check with an uncapturable unit wins. A third workable version, slightly more complex than Presto C, might be called Stationary King C -- checks may be met by capture or interposition; the first check forcing the opposing king to move wins. Yet a fourth version is Total Kamikaze C (see Cw1).
   In Bicolor C, kings are subject to check from their own units as well as the opponent's (the queen and queen's knight are exchanged in the array). Any move putting one's own king under attack from any unit is illegal (castling is impossible). The weakness of the d2/d7 squares is shown by the foolsmate 1 c4 c5 2 Qf5 d5?? 3 Qd7# (either Kxd7 or Bxd7 would leave the king in check from its own bishop). A variation, Bicapture C, allows players to capture their own units (as in Reform C (Ct2)) -- this mainly gives the king an extra resource to escape check (e.g. Kxf8 in the above game).
   In Reflex C, the object is to be mated by the opponent; a move giving mate must be made when it is available. In Contramatic C, the objective is the same; it is legal to put yourself into check but not the opponent. In both games, 'attacks' led by the king are common. See also Neutral King C (Cr2).

  Cx6 -- Other objectives
   There are a number of games, which I consider at best borderline CV's, whose sole objective is to move a piece to a certain location on the board. I cite only one example, the popular Racing Kings, in which all of the pieces (no pawns) are arranged on ranks 1 and 2, and the object is to move one's king to rank 8. Captures are allowed, but no move (including the king move to the eighth rank) may place either king in check. If White's king reaches the eighth rank first, Black has one more move to reach the eighth rank and draw. Dodo C is the same game in an alternate array without queens. Another variant is to race to the eighth rank and back to the first. Moving the king to the enemy thronesquare is a secondary method of winning in several variants [274, 457, 550] -- see also citadel (Terms).
   Parton also invented several simplified CV's he called duffery, in which only certain types of moves are allowed. The object is to capture the enemy king or to deprive the opponent of any legal moves (winning by stalemate). In Capturing Duffery, pawns move normally, but pieces can move only to capture. In Advancing Duffery, units can only move forward, becoming immobile when they reach the eighth rank. If neither king can be captured, the game is drawn. In Simpleton's Duffery, a player must give check if possible, otherwise capture if possible, otherwise move a pawn if possible, otherwise (if in check) move his king. If none of these moves are available, the player loses by stalemate (in Decimal Duffer's C, there is no priority of moves; a player in check may capture, interpose a pawn, or move his king to remove check; a player not in check may give check, capture, or move a pawn).
   In Unirexal C, Black has two queens at d8/e8 and no king. Her objective is to mate White as quickly as possible; White tries to avoid it (it is reasonable to play a two-game match; the player who mates in fewer moves as Black wins).  High-Low C combines chess and poker, allowing players to choose their own objectives; there are several variants. See also Kamikaze C (Cw1).

Cy -- Modification of number of players

  Cy1 -- Three-handed
   In three-handed variants, the objective is to mate one or both opponents, depending on the variant. Rules for disposition of units belonging to a mated king vary, as in four-handed variants. The oldest three-handed variant is Triple C, invented by Marinelli for an 8x8 board with three 3x8 wings. The central player is at a disadvantage; Tesche's C is an attempt to balance it using a very oddly shaped board of 96 squares (see back cover). Other three-handed boards consist of three half-boards (4x8) connected to each other (sometimes via a triangular central area). In [613, 632], each half-board is fully connected to each of the other two; in [545, 616, 665], each side of each half-board is connected to only one side of each of the other two. Dekle designed two- and three-handed games [615, 630] on the same board as [616]. Several hexagonal variants were designed for three players, or have variants for both two and three players (see Ck1). San-Kwo-Chi is a three-handed variant of xiang qi (see Cc4). The board consists of three half-boards joined into a hexagon (similar to [616]).
   Mad Threeparty C is a decimal variant for three players in which each player has two kings (one is marked with a star) plus the usual pieces, but no pawns. Each player tries to mate his left-hand opponent's starred king or his right-hand opponent's unstarred king, and cannot give check to the other two opposing kings. The game begins with the board empty. The players in rotation place one piece at a time in any vacant square; kings must be placed last, after which the game begins. Triscacia is a more conventional version on an 8x8 board with one king per side; each player has the normal pieces plus three pawns. Units are again placed one by one in rotation; Blue is restricted to ah13, Green in ad48, Red in eh48 (variant: kings begin at d1/b7/g7). Pawns are immobile, but once per game each player may convert a pawn to a queen after losing her original queen. Each player attempts to mate her left-hand opponent, and cannot make a move exposing the right-hand opponent's king to check from any of her units.

  Cy2 -- Four-handed
   The majority of four handed variants are played on a cross-shaped board consisting of an 8x8 board with a wing added to each of the four sides. Most often the wings are 3x8 (see cover), but 2x8 and 4x8 wings have also been employed. Among the many versions of this are: 115, 129, 226, 238, 242, 294, 359, 486, 626, 659, 660. In most four-handed partnership  games, players play clockwise in rotation (without consultation between partners). Partners' units cannot capture each other and hence do not check each other -- partnership kings may even be adjacent! It is forbidden to make a move which exposes your king or your partner's to check. Normally the object is to mate both opponents. The 'standard' forms of four-handed chess are those of Hughes and Verney -- full rules are given in 'codified' form in the Index -- see the rules sections M/O/Q/W/Z. A few variants (including CIF Four-Handed C, some variants of Chessnuts, and one version of QuadraChess) are free-for-alls in which each player plays alone. It is usual on 2x8-winged board to forbid rooks pawns to be captured on their initial squares. Luneburg C is a 2x8-winged variant with partners beginning on adjacent wings -- the same is true in the 'Hazelnut' variant (one of seven) in Chessnuts, also played on the W2 board. QuadraChess is a 4x8-winged variant with a number of interesting rules.
   One flaw in four-handed variants using rule Z1 (such as Verney's) is that pawn promotion is extremely unlikely -- even a rook pawn would have to make three captures. There are several ways around this -- one is to allow promotion by rule Z2 or Z3. In variants where partners are adjacent, rule Z2 allows normal promotion, but in an opponent's wing! In Trabue's C, pawns which reach either main diagonal turn and move thereafter toward the wing at the left or right (whichever is nearer) of the owning player (e.g. South's pawn starting at e2 moves west after it reaches e5; East's pawn at m9 moves North after it reaches i9). In Vendetta, pawns may turn sideways upon entering a side wing. H. Keatley Moore suggested in 1881 (see CE) that pawns be allowed to turn sideways after any capture. In the last three games, pawns promote normally when they reach the farthest rank of the side wing they turn towards.
   One method of adapting four-handed variants to a square board are placing each player in a roughly square arrangement in one of the four corners (as in the medieval Shatranj variant Acedrex de los Quatros Tiempos). Another variant of this type is Angular Four-handed C, played with eight pieces per side plus two (optional) pawns as guards. Arrays may be found in NJENO. Quatre Quest-Chess is a four-handed version of Quest-Chess (see Cn1), played on a modified 11x11 board. This is a free-for-all game in which the first player to checkmate any opponent wins. Quatrochess is a 15x15 variant with an impassable center gh78 (see [87]), and a 5x5 array in each corner, adding Gi/Gi/M/M/F/W/V/X/C to the normal forces for each player.
   Another way to play four-handed on a square board is to place each player in a normal array along roughly half of one side (adapted from Chaturaja). A decimal version using modern moves is Neo-Chaturanga. Head's C is played on a 12x12 board with a full 16-unit army for each player, but partners are adjacent. A mated player plays on with the remainder of her army after removing her king. Chatty C is an 8x8 version with formalized partnership communication as in contract bridge.    Naylor-Ower C is played with partners side by side on a 10x8 board. Slater's Four-handed C is played likewise on an 8x8 board. Crompton's C is a strange 8x8 variant in which rooks and knights are absent from the array, appearing only by promotion.
   In Petroff's C, 4x4 squares are placed between the wings of a board with four 2x8 wings, making a board which fits in a 16x16 area (equivalent to a 12x12 board with expanded corners -- see the back cover). Each player has the 4x4 area to his right as an extra playing area, wherein he places an extra rook, bishop, and knight as desired. Note the barriers in front of each area -- the dark lines cannot be crossed (though knights can leap them).
   In WGR7 we suggested Balanced Multimove C, a move patterm which can be used with any form of three-handed (1,2,3,3,...) or four-handed (1,2,3,4,4,...) chess.

  Cy3 -- More than four (or indefinite)
   Betza devised Multiplayer Melee C, a method of adapting play to any number of players. Each player has a half-board which can be matched to any other player's half-board, allowing moves from one to the other. See Cy1 for three-handed boards using   a similar idea. Sceptre 1027 A.D., reviewed in WGR7, can be played by two to four players. Six-handed variants have been proposed with three boards placed side by side (Godneff's C uses three boards end to end, pawns promoting at the eighth rank of their starting board). Plex is a six-handed variant played on a board tiled with hexagons. Verney invented an eight-handed variant played on a 16x16 board with four 3x16 wings, totalling 448 squares (rules analogous to his four-handed  game).  Chess-O-Rama is an eight-handed variant played on a set of special interlocking boards.

  Cy4 -- Team
   Double Bughouse C (a misnomer; Double Chessgi would be more descriptive) is a popular over-the-board game, played most often by two teams of two players.  Jeremy Graham wrote to me that it dates back at least to the early 1960's.  Each player plays one of the opponents on a separate board. When a capture is made, the capturing player gives the captured unit to her teammate, who places it in a reserve, where he can enter it at any time as in Chessgi. There is no alternation of moves between games -- each game proceeds each its own pace (using separate chess clocks). The first player to checkmate his opponent wins for his team. Any number of pairs can participate; captures are passed to the board at the immediate right (the far right board passes captures to the far left). A more limited form is Exchange C.



Sample Games
   The best sources for examples of a wide variety of CV's are the books in French by Boyer, Gollon's book, and Cohen's bimonthly NA column.  In annotated games, text moves are in boldface to set them off from notes. In progressive games, symbols (?!) after a move number comment on the whole series; comments on individual moves follow them directly.

Game 1 -- Balanced Marseillais Chess   John McCallion vs. Leo Spencer   NOST 1987 Postal Championship  notes by JM
1 d4 d5/Nf6  2 Bf4/Bg3 Nc6/Qd7!  3 e3/Nf3 Nxd4/Nxf3+  4 gxf3/Nd2 c6/e6 (protecting the queen) 5 Nb3/a4 Qe7/e5 6 Bxe5/Bd4?! (A move which seems to have impressed Leo but, still thinking it dubious, I regretted it as soon as I had made it) c5/cxd4 (my original idea of 7 Nxd4/Bb5+ did not seem to work after 7...Nd7/Qf6! So...) 7 Qxd4/Bb5+ Nd7/Rb8 8 Rg1/Bxd7+ Kxd7!/a6  (The king move releases the f8 bishop from a potential pin and thus prevents 9 Qxg7/Qxh8.  I was starting to think that the impetus of my attack would soon vanish) 9 Rg5/Rxd5+ Kc7/Be6  (It was now MADDENING to note that a5/Qb6 was not mate because of the flight to c8, and Rd8/Qb6 was not possible because the queen is unguarded.  Only at the very last moment did the solution hit me like a ton of bricks, and how I laughed at my own stupidity for not learning much better from Leo...) 10 Rd6 (blocks off the queen)/Qc5#.

Game 2 -- Dynamo Chess, Philip Cohen vs. John McCallion, 1986 NOST Postal Championship (first published in NA297).
1 Qd1d4(d2d6) (threatens Qd4a7(a7E)...Ra8E(Qa7E) Ra1(a2a8=Q)) Qd8c7(c7b6) 2 Ng1e2(e2c3) Bc8d7(d7e6)  3 Nb1c3(c3d5) Qc7c5  4 Bc1g5 Nb8d7(Bd7f6) 5 Rh1h3(h3h4) Ng8f6(Bf6e4) 6 Bf1d3(Ne2c4) Be4g2(g2E) 7 Rh3e3 Nf6d5(d5b4) 8 Nc3e4 (threatens Ne4d6+(d6c8=Q)) Bg2E(Ne4E)  9 Bg5(e7E)? Qc5e5(Nd5f5) 10 Re3e4(Ke1e2)? Nf5d4+(Qd4b3)  11 Re4g4(Nd4e4) Nd7e5(Qe5f3+) 12 Ke2f1 Qf3e2+ 13 Resigns

Game 3 -- English Progressive, Tony Gardner vs. Andrea Mori, NOST Postal Championship 1988, (first published in Eteroscacco 50)
1 Nf3  2 d6 Nf6  3 d4 g4 Bg2  4 Bxg4 c6 Nbd7 Qb6  5 a3 b3 Nc3 Nd2 Bb2 6 Ne4 Ndf6 e5 OOO Bh5 Be7  7 Bxe4 Nc4 Qd3 Ra2 Ba1 h4 e3  8 Nxe4 f5 Bg6 Qc7 exd4 Bf6 d5 Rhe8  9 Na4 Ncb2 b4 Qc3 exd4 f3 h5 OO // fxe4  (White begins blocking his units)  10 f4 dxe4 b6 c5 Kb7 Rd7 Reb8 Bf5 g5 Bxd4+ 11 Kg2 (forces a pawn check on Black's next series) Nxb6 N2a4 Qxc5 b5 c3  h6 Rb2 Rd1 // Nxd7 Qxc7+  12 Kxc7 a5 Bxd7 Be5 f3+  13 Kf2 Nb6 a4 c4 Rd6 Rb1 Bxe5 // c5 Rxd7#.

Game 4 -- Extinction Chess, Walter Roessner vs. Michael Keller, Sep. 26, NV'87 (first published in NA304). Added notes by MK and rws.
1 e3 e5  2 d4 exd4 3 exd4 Nc6  4 Nf3 d5  5 Bb5 Bd7? (better is ...Qd6 -- rws). 6 Ne5!? (sets a trap, but O-O is preferable -- rws) Nxe5 7 Qe2! Bxb5? (worse is 7...Ne7?? 8 Qxe5#.  7...Be7? also loses eventually after 8 Bxd7. 7...Qe7 seems O.K. (best is ...c6 -- rws)). 8 Qxe5 Kd7 (...Be7 loses to Qxg7#) 9 Qxd5 Bd6  10 Qxf7#.

Game 5 -- Highcastle Chess, John McCallion vs. Adrian Groenendyk, NOST Postal Championship, 1988 (notes by JM)
 [x*y indicates the unit at square x 'castles' with the unit at y]
1 e3 e5 (...Nf6 is safer, preventing a queen sortie to h5 followed by f2*f7. However, 2 Qh5 now seems adequately met by 2...e5*Qh5) 2 Bb5 (threatening d2*d7 check) Nc6 3 Bb5*e5 (3 Qh5? is easily met by ...Nf6!, when f2*Nf6 is not possible because the knight would check on f3. 3 Qf3, threatening Qf3*Nc6, is met by ...d5, when c2*Nc6+ would leave the bishop under attack from c3) 3...Be7?? (simple and good seems 3...Nf6) 4 Qh5! (White at last achieves his primitive ambition, and shows how dreadfully placed is the Black bishop) 4...Nh6 (Forced. Of course ...g6 is answered by 5 c2*g6) 5 f2*f7+! Kf8? (At the time, I never considered ...Nh6*Nc6!, but it seems to leave White with nothing better than the gain of a pawn, admittedly with a superior position, by 6 Qxf3) 6 f4*Kf8+! Kxf6  7 Nxf3 (b2*Kf6+ was the first move I saw, but things became confused after Kxc2. The move chosen is orthochessic but convincing)  7...Bf8 (a tragi-comic admission of defeat) 8 Nf3*Kf6+ (Qg5+ is greeted by Nc6*Kf6 with tiresome complications and obstacles) 8...Resigns (8...Ke5 is met by 9 h2*Ke5+ and mate follows).

Game 6 -- Knightrider Bouncy Chess, Stuart Conquest vs. Patrick Donovan, May 27, 1985 (notes by PD)
1 Nb1c4+ (via a3) d6  2 b4 (Nxa8 would let black trap the N by 2...b6) Ngf6 3 h3 h5+ (via h7, g5, f3)  4 Nf3 Bg4!  5 hxg4 hxg4  6 Rxh8 gxf3 (Black is ahead by the exchange of R and B for N) 7 gxf3 Nf6xf1 (via h5, f1 -- the other N protects it via d7, f6, h5)  8 d4 Nf1f6  9 c3+  (the white queen checks via a4) c6  10 Qc2 Nb8c7 (via a6; the white Q is now pinned) 11 a3 Qc8  (threatens 12...Qf1#)  12 Rh1 Qe6  13 d5 Nf6xf3+.  White resigns, as his Q is lost.

Game 7 -- Mutation Chess (MU), Tiziano Sala vs. Michael Keller, 1st Heterochess Olympics
1 e4 2 e5 Nc6 3 Nc3 d4 d5  4 Bb4 Bxc3=N d6 Nd4  5 bxc3=N Nf3 Nxd4 Nf3 Be2  6 f6 b5 b4 bxc3=N Nxe2=B Bxf3=N+  7 gxf3=N Nxe5=P exf6 fxg7 gxh8=R Rxg8=N f4  8 Qd7 Qb5 c6 cxd5 dxe4 e3 Bb7 Bxh1=R#.
Mutation was perhaps the most interesting event of the Olympics, as John Bosley invented the game especially for this tournament, hence none of the players had ever played it before.

Game 8 -- Progressive Circe, Michael Keller vs. Roberto Salvadori, First Heterochess Olympics.  () is the return square of a captured unit.
1 e3 2 Nc6 Nh6 3 Bc4 Qf3 Ke2 4 e5 Bb4 Qf6 Ke7 5 c3 e4 g4 g5 gxf6(d8)+ 6 Kd6 Kc5 Kxc4(f1) B:c3(c2) ... Nd4#
Note by Salvadori:  In CR.PR., there are situations that are very funny. For instance : 1 d4 2 e5 d5 3?? dxe5(e7) e4 Cf3 4 dxe4(e2) ... Dxd1#.  The capture of the black queen is impossible; she would give check on returning to her starting square.

Game 9 -- Progressive Take-All (PTPR), Vaclav Hlavaty vs. Michael Keller, 1st Heterochess Olympics. Notes by MK (thanks to Giorgio Ervetti).
1 e4  2? Nc6 Nf6  3? Qf3 Qxf6 Qxc6  4 bxc6 Ba6 Bxf1 Bxg2 5 e5 e6 exf7 fxe8=Q Qxd8  6 Rxd8 Rb8 Rxb2 Rxb1 Rxa1 Bxh1  7 Ba3 Bxe7 Bxf8 Bxg7 Bxh8 Bxa1 Bd4  8 c5 cxd4 d3 dxc2 c1=Q Qxe1 Qxg1 Bd5  9 f4 f5 f6 f7 f8=Q Qf1 Qxg1 Qxa7 Qxc7  10 Resigns.

Giorgio Ervetti suggests that Black should be winning after the 5th series, but I cannot find better than a draw for any alternate Black 6th (improvements are welcome). Some possible lines are:
6 g6 Bg7 Bxb2 Bxa1 Rhxd8 Bxh1 7 d4 d5 d6 dxe7 exd8=Q Qxa8 Qxh1  8 d5 d4 d3 dxc2 cxb1=Q Qe4 Qxh1 Qxg1   9 f4 f5 fxg6 fxh7 Be3 Bxg1 Bax7 Kd1 Kc2 wins (or 8 g5 g4 g3 gxf2 fxe1=Q Qxc1 Qxg1 Qxh1   9 Nd2 Nf1 Nh3 Nxh1 Nf2 Ne4 Nf6 Nxd7 h3! wins)
6 Rxd8 Rb8 Rxb2 Rxb1 Rxa1 Rxa2 7 Bb2 Bxg7 Bxh8 Ke2 Nh3! Ra1 Rxa2 8 Bxh3 Bg4 Bxe2 Bc4 Bxa2 Bh6 Bxe2 Bf4 9 Be5 Bxf4 Bxc7 Bb8 Bxa7 Bc5 Bxe7 Bd6 c3! Draw (or 8 Bxh3 Bg4 Bxe2 Bc4 Bxa2 Bg7 Bxh8 Bf6  9 d4 d5 dxc6 cxd7 d8=Q Qxe7 Qxf6 Qa1! c3! wins)
6 Rxd8 Rb8 Rxb2 Rxb1 Rxc1 Rxa1  7 h4 h5 h6 hxg7 gxf8=Q Qxh8 Qxa1  8 h5 h4 h3 h2 hxg1=Q Qxe1 Qxa1 Qxh1  9 d4 d5 d6 dxe7 e8=Q Qxd7 Qh3 Qxh1 Qc1! 10 Bd5 Bxa2 Bf7 a5 a4 a3 a2 a1=Q Qxc1 ... Draw

In the end it is Black's 8th series which is incorrect:
8! c5 c4 c3 cxd2 dxe1=Q Qxg1 Qxf2 Qxc2  (White can just queen the a pawn and capture the Black Q, but cannot stop the c/d pawns)  9 Bxa7 Bb8 a4 a5 a6 a7 a8=Q Qa2 Qxc2  10 Black promotes and wins.  If 7 ends ...Bc3, 8! d5 d4 dxc3 cxd2 dxe1=Q Qxg1 Qg8 Qf8 wins  (White has too many pawn moves left to play himself into stalemate).

Game 10 -- Shoot Chess (Rifle Chess with obligatory captures), Ray Brooks vs. Patrick Donovan, postal 1986
1 e4 c6 2 e5! e6 3 c3 Bc5  4 Qc2 Bxf2 5 Qxf7 Bxg1 6 Be2 Rxh2 7 Rxh8 Qe7 (to answer 8 Rh8 by 8...Qf8 9 Rxg8 Qxh8) 8 Qe4?? d5  9 Qxd5 Nd7 10 Qxc6 Nxe5 11 Qxb7 Rb8 12 Qxe6 Qxe4 13 Rh8 Qxe2+ 14 Kf1 Rxb2 15 Rxg8+ Nf8  16 Rxf8+ Kd7  17 Rxc8 Rxh8  18 d4 Bxd4  19 Bf4 Rxb1 20 Bxb8 Qf6 21 Rd1+ Kc8 22 Rc1 Qxf4+ 23 Ke1 Qxc3 24 Rxc5+ Kd8 25 Rd1+ Ke8 26 Rd3 Qa1+ 27 Resigns.

Game 11 -- Triplets, Dave Voorhees vs. Michael Keller, NOSTvention 1990 Championship, Sept. 29, 1990, final round.  Originally published in NA324. Notes here by MK.
1 e4 e5  2 Nf3,h3 Bc5,d6  3 Be2,O-O,a3 Nf6,O-O,h6 4 Nc3,Kh1,b4 d5?,Bd6,Kh8 (loses a pawn)  5 exd5,Kg1,Bb2  Kg8,Bf5,e4  6 Nd4,Kh1,a4? (White gives it back) Kh8,Bxb4,g6 7 Nxf5,Kg1,a5 gxf5,Bxc3,Kg7 (doubled pawns are bigger weak spots than in orthochess; White's next avoids one) 8 Bxc3,Kh1,d3 Kg8,exd3,Nxd5  (Black gains a pawn) 9 Qxd3,Kg1,g3 Nxc3,Kg7,a6 (Black exchanges his only developed piece) 10 Qxc3+,Kh2,h4 Qd5,Kg6,c6 (trying to restrict White's king)  11 Qf3,c3,Kg1 Qxf3?,Kf6,c5 (exchanges another developed piece and helps white's bishop find a good spot) 12 Bxf3,Kg2,c4 Kg6,Ra7,f6 (Black has no good moves to free a queenside pawn) 13 Rfd1,Kh3,h5+ Kg5,Re8,f4 (Trying to run White out of pawn moves) 14 g4,Kg2,Rd5+  Kh4,Rc8,b6 (too late to free a pawn) 15 axb6,Kh2,Ra5  Rb7,f5,Kg5 (both pawn and king moves are forced) 16? Kh3,Be2,f3 (e.g. Rxc5,gxf5 wins at once) Kf6,fxg4+,Re7 17 fxg4,Bf3,Kh4 wins.

A Challenge From Computers -- and a Challenge To Computers
   In the past year or so an extremely strong chess-playing computer program called Deep Thought has been making waves. It has beaten several grandmasters, and had a drawn position against former world champion Anatoly Karpov before overplaying the position and  losing.  Many observers believe that within a decade, this program will be strong enough to defeat the world champion in an official match. (This has been predicted for decades, but this is the first program which appears potentially capable of it).
   If this happens, will there be an outcry for a new form of chess at which computers will be less successful? This is mere conjecture, since over-the-board play would not necessarily be affected, though changes in the rules (such as faster time controls) to eliminate adjournments might be introduced. Postal play could scarcely be unaffected -- there is already debate about the potential (ab)use of computers there -- and eventually computers capable of beating any human player would be available to everyone.
   But possibly human vanity would demand that major changes to the game be made. (Even in the absence of computers, increasing frequency of draws and reliance on published opening analysis may eventually bring about a change.) If so, what form would the new chess take? One possible road would be to increase the size of the board and add new pieces, but the increase in size would have to be substantial to put brute force calculation out of the reach of present computers. A typical decimal variation (10x10 board with two new pieces per side and ten pawns) probably would not be sufficient -- a well-written program today could play Grand C as well as most human players. A third row of units (as in Tamerlane's C) or a 12x12 board would probably be necessary. But a variant requiring an entirely new board and pieces would meet strong opposition as a candidate for a new form of chess.
   A second road would be a variant in which modified rules of play greatly increase the number of combinations. One likely candidate might be shogi -- because all of the units remain available throughout the game,  the  number  of  combinations  remains high.  Possibly the international chess community would turn to some form of chessgi to replace today's chess. Another way to increase complexity would be to play a multi-move variation. Doublemove may not be complex enough; a progressive variant would be. Ordinary Scottish or Italian Progressive is too drastic to meet with the approval of present-day players; it is too different from orthodox chess. Let us instead suggest a possible dark-horse candidate: English Progressive. This would bring about the desired increase in complexity (no computer can handle a progressively larger number of combinations using today's exhaustive methods), yet the game is close enough to orthodox chess in its patterns of development to be a possible candidate for the chess of tomorrow.
   While on the subject, it is worth noting that there are very few computer programs now on the market which play CVs. Except for a handful of programs for playing xiang qi, Distant Armies, and the forthcoming Shogimaster, there is next to nothing available! It is perhaps too much to ask today for a computer to be able to set up its own pieces as in pre-chess, to make more than one move per turn, or reenter captives as in chessgi, but playing any semi-orthodox variation should be well within the ability of a modern program. How about a flexible program with options for several different board sizes, a selection of units beyond the standard ones (e.g. Berolina pawns, nightrider, fers/elephant/wazir/dabbaba, amazon/chancellor/cardinal), and perhaps a few other options?

Additional Pieces
   Hundreds of pieces have been invented, many of them for fairy chess problems. Listed here are a selection of pieces, including those most frequently seen in variants. To clarify the shorthand for moves, the orthodox pieces are listed also. More fairy pieces may be found in AJS, JENO, GFC, OCC, and VC 1-3 (see Bibliography).

A  Amazon           Q + N   
An Antelope         (3,4)  
Ap Arrow Pawn       1O {2O} [1D]
B  Bishop           *(1,1)   
Bp Berolina Pawn    1{2}DF [1OF]
C  Cardinal (1)     B + N   
D  Dabbaba          (0,2)    
E  Elephant (2)     (2,2)  
F  Fers (Firz)      (1,1)  
Fa Falcon           *DF + *OB 
G  Gold General     1O + 1DF
Gi Giraffe          (1,4)    
Gn Gnu (Wildebeest) N + M
H  Dragon Horse (3) B + W
Hu Hunter           *OF + *DB 
I  Biok             B [R]     
K  King (4)         W + F   
M  Camel            (1,3)
N  Knight           (1,2)
Nr Nightrider       *(1,2)
O  Roshop           R [B]
Oc Octopus (5)      (1,1)/*(0,1)
P  Pawn             1{2}OF [1DF]
Q  Queen            R + B
R  Rook             *(0,1)
S  Silver General   1D + 1OF
Sp Spider (5)       (0,1)/*(1,1)
Sq Squirrel         D + E + N
T  Dragon King (6)  R + F
U  Unicorn (7)      *(1,1,1)
V  Counselor (4)    W + F
W  Wazir            (0,1)
X  Chancellor (8)   R + N
Z  Zebra            (2,3)

D -- diagonally   (M,N) -- leaps to square M ranks and N files
O -- orthogonally         (or vice-versa) away       
F -- forward     [] -- different capturing/checking move
B -- backward    {} -- optional first move       
S -- sideways    * -- Rider; makes series of leaps in same direction
1 -- one square           + -- combines powers
2 -- two squares (cannot leap)   / -- followed by

Notes:
(1) Also called archbishop, a name also used for other pieces, such as the combined bishop-unicorn in Kog 3-D C. The name cardinal has been used by Edward Lasker, Freeling, and Schmittberger. The usual name among problemists (coined in 1925 by Maus) is Princess.
(2) The original 'bishop' from Chaturanga, called Alfil in Shatranj. The elephant in xiang qi does not leap.
(3) Promoted bishop in shogi.
(4) The king is a royal piece; the counselor (also known as mann, regent, vinea) has the same move but is non-royal.
(5) 'Skew riders', with names suggested by Schmittberger. A spider at a1 can reach b3/c4/d5/e6/f7/g8 and c2/d3/e4/f5/g6/h7; an octopus can reach b3/b4/b5/b6/b7/b8 and c2/d2/e2/f2/g2/h2. Neither piece can leap occupied squares. The Zurafa in [601] is an octopus, but must go at least to b4 or d2 (b5 or e2 in [602]).  The spider is found in [667]; a spider-like piece is also found in [393].
(6) Promoted rook in shogi. T is the initial letter for the rook in most Western European languages.
(7) Three-dimensional bishop (see Ci1)
(8) The name chancellor has been used by Betza, Capablanca, Dawson, Dekle, Foster, Gardner, Legler, Paletta, and Parton, among others.   The usual name among problemists (also due to Maus, 1925) is Empress, a poor name for a piece less powerful than a queen.

Additional Rules

B back rank (and other Cb) arrangements
1 randomized back rank
2 symmetric (e.g. White and Black kings placed on same files, unless <>  -- crosswise)
3 bishops must be placed on squares of opposite colors

C castling variations
- no castling
(numbers)
x   king may castle by moving x squares to either side, the rook hopping over the king to the last square the K passed over (orthochess = 2).
m/n king may castle by moving m squares towards the far rook (usually the a rook) or n squares towards the near rook (usually h).  E.g., in Chess Tweedle, castling may be Kd1b1/Ra1c1 or Kg1i1/Rj1h1; in Lilliputian C, castling may be Kb1/Rc1 or Ke1/Rd1.
(letters)
a   king may make one knight move per game, even to capture or escape check. In games with castling [589], a king which castles loses its power to make a knight move and vice versa.

E en passant/doublestep variations (n = no en passant)
1 no doublestep for pawns, hence no e.p.
2 pawn can doublestep, normal e.p.
3 pawn can triplestep with analogous e.p. (e.g.: BPd5, White plays e2e5, black captures e.p.
4 pawn can quadruplestep with analogous e.p.
5 pawn can triplestep or doublestep on its first move, and may double-step on its second move if it singlesteps on its first (e.g. on a 10x10 board, a pawn can advance as far as the fifth rank from the second or third), with corresponding e.p.
6 pawn can singlestep or doublestep at any time

M effect of mate on mated king's units (units remain, immobile but capturable (unless 1,2,3). Cannot check or capture (unless 4,5)).
1 all units removed
2 units remain but are uncapturable
3 units belong to mating player
4 units still give check
5 no effect -- king removed; remaining units can move and capture
6 units return to normal if mate relieved
7 opponents combine into one force
8 game ends (i.e., object is to mate only one opponent)
* effects of stalemate

N number of players
2 2-handed
3 3-handed
4 4-handed, playing in partnerships
4a 4-handed, each playing individually

O other rules for pawn movement/promotion
1 when friendly pawns meet head-on, either can hop over the other (two
   squares forward) to an empty square
2 pawns move towards back ranks of any wing they enter
3 rook pawns cannot doublestep
4 pawns reaching partner's second (5 = back) rank 'turn around' and
   begin to move like partner's pawns

P pawn promotion -- pawns promote to any piece listed after the equal
   sign. Normally this is any piece present in the array except King.
   Some minichesses and other CV's lack one or more of the orthodox Q,
   B,N,R. Unless specified, promotion to absent pieces is prohibited.
== promotion to lost piece only; the pawn cannot advance to the eighth if
   there is no piece to promote to
=| promotion to piece standing on file in array (e.g. Pa8 promotes to R).
==| promotion to piece standing on file in array only if that piece lost.
=+ promotion to piece(s) in addition to orthodox QRBN
() promotion zone -- ranks on which pawns may promote (orthochess (8))
BP,WP -- promotion for one side different from normal (cf. [669])

Q queen location on four-handed board
1 left of king
2 right of king
3 on black square
4 on white square

R rotation chesses
() regions which can rotate (* -- any square of indicated size)
  If rotation areas are concentric, outer ones are rings (e.g. in [203],
  ring cde3/f345/def6/c456 rotates independently of de45).
 Directions of rotation:
a 90 degrees (1/4 turn) anticlockwise
c 90 degrees clockwise
h 180 degrees (1/2 turn)
e 90 degrees in either direction at choice of moving player

 Conditions:
AEIOU actuated -- rotates whenever a unit moves Across (into, then out of), Externally (completely outside of), Into, Out of (starting within), or Upon (completely within) it
P permanent -- rotates after every half move
R restricted -- cannot rotate if it contains enemy units

V winning methods besides checkmate
1 stalemated player loses
2 player with lone king loses (robado)
3 king entering enemy thronesquare wins

W wing size for four-handed boards
2 four 2x8 wings, total 128 squares
3 four 3x8 wings, total 160 squares
4 four 4x8 wings, total 192 squares

Z promotion zones
1 back rank of side wings (usually by repetitive capture)
2 back rank of opposite wing (normally partner's wing)
3 far edge of side wings

Inventors 
The following list of inventors is alphabetized by last name, and cross-indexed with a list of their inventions by index number. Inventors with large numbers of CV's have the quantity in parentheses before the list. In some cases credit is given for an idea or array.

ra   Robert Abbott 455,646
gia  Giuseppe Arbrile  141
ga   Gabriel Authier  58  
lpa  Louis Paul d'Autremont 15
hdb  H. D. Baskerville  51
jdb  John D. Beasley 111   
cb   Charles Beatty  488   
rob  Romeo Bedoni  57     
bdb  B. de Beler  61      
db   Donald Benge 490,494  
hab  Howard A. Bergerson 648
jb   Jacques Berthoumeau (60,452,580)            
rb   Ralph Betza  57:(19,23,38-40,56,59,64,68,73,83,85,106,108,110,137,140,142,143,149,155,189,199,201,209,223,241,255,261,287,303,336,346,351,377,379,380,404,410,429,431,434,460,463,
                  483,517,520,578,586,587,594,628,641,649,652,661,669)       
heb  Henry Edward Bird  62   
kb   Keith Bogart  66    
mb   Marco Bonavoglia 257
jeb  John E. Bosley  (15,323,406)          
jpb  Jean-Pierre Boyer  130 
job  Joseph Boyer   (148,224,267,343,420,555)
rab  Ray Brooks  330   
rbb  Robert Bruce 44,69,121
eb   Erich Brunner 596,640 
erb  Edgar Rice Burroughs  313
sac  Salvio Cagliostro 589 
wc   Walter Campbell  600  
wsc  W. S. Campling  144  
joc  Jose Raul Capablanca 77,78
gc   G. Capellen 244   
pc   Pietro Carrera  82  
rc   Roberto Cassano  168
mc   Mannis Charosh  (63,328,361,512,643)     
ic   Irving Chernev  643 
jrc  John R. Cleaveland 357
pmc  Philip M. Cohen   25:(33,65,138,139,164,214,233,239,248,378,415,424,425,439,469,510,513,522,563,565,593,623,649,662,677)
stc  Stuart Conquest 330   
lsc  Lawrence S. Crane  471   
gec  George Crompton 161
jec  J. E. H. Creed 70,360
gac  Garry Crum  423 
eic  E. I. Csaszar 503
trd  T. R. Dawson (175,236,254,372)
sd   Steve DeFluiter 337  
grd  George R. Dekle  28:(98,104,151,163,167,184-186,232,274,284,302,340,349,350,354,371,382,477,491,572,575,615,629,630,633,637,672)
evd  E. van Dien   462
gd   Giuseppe Dipilato 476
pd   Patrick Donovan 67
ld   Lord Dunsany 210
epd  E. Paul Dyson  432
be   Bernd Eickenscheidt 373
dae  Douglas A. Engel  489
kf   Karl Fabel  605
aef  A. E. Farebrother 5,450
pf   Paul Felisch  246
clf  C. Lavington Fielder 558
af   Albert Fortis  370
brf  Benjamin R. Foster 91
cf   Christiaan Freeling 265
rlf  Richard L. Frey  449
fg   Fred Galvin (145,204,481,509)
hcg  H. C. Garner 321
wig  William Geary  507
tg   Toyota Genryu 621
ag   Alexander George 511
brg  Bruce R. Gilson  245
eg   Ed Ginsberg 590
wg   Wladyslaw Glinski 280
wfg  W. F. H. Godson 263
kjg  K. J. Goodare 604
swg  Solomon W. Golomb 103
rg   Richard Grandy 190
pg   Perry Grant  567
dg   Doug Grant 196
rrg  Roberto R. Gravina 473
hdg  H. D. Grayber (574)
atg  A. T. Griffith 270
wgg  William G. Groman  297
jag  James A. Gutzwiller (14,311,389,461,527)
cch  Chi Chi Hackenberg 123
dh   Don Haffner  31   
wh   Wally Hagemann 21,75,331
mh   M. Hanazawa 27   
jgh  Julian Grant Hayward 275
wgh  W. G. Head   276  
ah   Al Helzner 213   
jh   John Holland  298 
fh   Frank Hopkins 559 
mah  Malcolm Horne  500 
bvh  Baron von Hoverbeck 479
jth  J. T. Howard 292  
csh  C. S. Howell 293  
meh  M. E. Hughes-Hughes 294
ji   John Ishkanian 401  
gpj  G. P. Jelliss (28,225,654)          
gwj  Gerhard W. Jensch  584   
phj  P. H. Johnson 7,515  
rj   Rick Johnson  315  
maj  Michael A. Juhasz 207,347
pk   Peter Kahl  215    
kk   Karl Kaiser 317   
pjk  Prince Joli Kansil  381 
ajk  A. J. Karwatkar 363  
mk   Michael Keller 45,291 
ldk  Legall de Kermeur  562 
rok  Robin King  43   
hk   Hans Kluver  215  
egk  Ervand G. Kogbetliantz 332
hwk  Harold W. Kohn   592  
ek   Ejnar Kristensen 335
mxl  Max Lange  561  
eml  Emanuel Lasker  319,417
ml   Maxwell J. Lawrence 36,627
bgl  Benjamin G. Laws   507   
ll   L. Legan 41,193,237
hl   Hugo Legler 342   
el   Einar Letzen  344
cgl  C. G. Lewin  560 
jal  John A. Lewis  345
rl   R. Loiseau 452,580
tl   Thomas Long  20    
fm   Ferdinand Maack  501
fjm  Frank J. Marshall 514
tm   Theodorick Martin  359 
fim  Filippo Marinelli 251,634
gvm  Gabriel V. Maura  394  
fgm  Frank G. Maus (84,109,146,156,221,365,612,650)
jm   John Menke   448  
mmm  M. Michelson  278
dlm  Donald L. Miller  574
dm   David Moeser  18:(13,14,46,202,235,279,347,389,414,458,461,495,524,536,556,579,585,619)            
pm   Pierre Monreal 130,320
fvm  Frank Vigor Morley  398   
mm   Moe Moss   399   
anm  Anatole Mouterde 400   
hm   Hans Multhopp 99   
ln   Leo Nadvorney 421,573 
jln  J. L. Nayler  407   
en   Edmund Nebermann  53  
lhn  Lawrence H. Nolte  116   
pn   Paul Novak  67,422
mo   Michel Olausson    89
ro   Reb Orrell 42,326,655
eo   E. Ower  407    
avp  Anthony V. Paletta  32:(16,32,87,136,154,157,198,228,249,281,282,285,289,301,383,384,428,451,472,487,505,521,544,568,570,603,609,617,618,657,667,673)
alp  Alan Parr  290    
vrp  Vernon R. Parton  63:(2,9,12,22,26,55,72,79,80,86,102,119,124,125,152,165,170,173,174,177,178,180-183,187,188,197,208,216,264,271,273,300,310,322,355,364,369,374,
                       391,392,408,411,412,420,434,440,441,496,516,528,530,533,546,557,576,597,601,636,642,651,675)
ap   Anthony Patton 631
ep   Ed Pegg (117,286,386,599)
rap  Ragnar Persson 34
aop  A. von Petroff 453
np   Nenad Petrovic 305
wp   Wilfried Pflughaupt 396
fp   Francesco Piacenza 30
rp   Roger Powell   1
vp   Vladimir Pribylinec 166
dp   David Pritchard 418,620
jdq  Jesse del Quadro  312
jq   Jack Quinn  238
rmr  Roman Raia  105
lr   Lav Rajcic 305
ar   Alex Randolph 362,409
whr  William H. Rawlings  (5,450,464,478)
mer  Mike E. Rice  234
igr  Ian G. Richardson 95
hr   H. Richter  107
adr  Arnous de Riviere  525
dor  3rd Duke of Rutland 531
rr   Roger Ryan  337
pr   Porterfield Rynd 194
hs   Honey Sauberman 486
bws  B. William Schmidt 432
rws  R. Wayne Schmittberger  10:(10,65,219,229,230,252,390,415,608,671)
ks   Karl Schulz (179,231,295,316)
bs   Bernd Schwarzkopf 373
wbs  William B. Seabrook 523,553 
jjs  J. J. Secker 6,529   
ros  Roland Seegers  535   
hjs  Henry J. Self  545    
jes  Jeffrey Shaffer 318   
jos  John Shepherd 24   
dls  David L. Silverman 569,577
es   Eliot Slater 122,247,564
as   Adam Sobey  635    
js   Jon Spencer 212   
afs  Alphonso F. Stanonis 132
ws   Walter Stead  269    
srs  Stephen R. Stockman 242
lt   L. Tabi  508   
nbt  Nassouh bey Taher  35
mht  Michael Henry Temple 333
wt   Walter Tesche 611    
jst  John S. Thayer 653   
ft   Frank Thibault 466  
iht  Isaac H. Trabue 626  
llt  L. Tressau 150,220,588
brt  Bruce R. Trone  20:(47,48,88,100,120,126,203,268,304,306,339,376,395,423,480,498,542,551,566,647)
cmt  C. M. B. Tylor  (17,18,37,437,502,622)
kv   Ken Valentine 656  
hev  Helge Em. de Vasa  192  
jbv  Johannes B. Verdonk 467   
ghv  George Hope Verney 133,217,660
jdv  Count J. de Villeneuve 484
nv   N. Voss  591    
ssw  S. Waider 665    
aw   A. Wardley 666   
bww  B. Walker Watson 454
siw  Siegmund Wellisch 670
avw  A. von Wilpert 674
sw   Steve Wilson 433
dw   Dan Wright 414
bz   Bruce Zimov  327,341,358
rz   Robert Zubrin 616


   The two most prolific inventors, both in sheer numbers and in numbers of successful games, are Ralph Betza and V. R. Parton. Betza's variants appeared frequently in NOST-Algia between 1973 (NA160) and 1982; he is still inventing occasional variants today. Among his creations, Avalanche, Chessgi, and the Co-Chess family (particularly Transportation) have become staples in NOST and elsewhere. Parton, who died in 1974, had many variants published in various magazines from the 1950's onward, and later published a series of pamphlets (see Bibliography) describing some of his creations. His two greatest interests were decimal (10x10) chess, and variants based on Alice in Wonderland (e.g. his first published variant, Rettah Chess, is Hatter spelled backwards).  Other prolific inventors include Philip M. Cohen, George R. Dekle, David Moeser, Anthony Paletta, R. Wayne Schmittberger, and Bruce Trone. Special mentions to Mannis Charosh, who invented U-Chess, as well as Relay Chess and its most important variant Knight Relay; and Fred Galvin, who has only 4 listings, but all major ones: Compromise/Refusal, Doublemove, and Push (which developed into Dynamo).

Bibliography
Note: I have listed some important works which I have not personally consulted; these are marked with asterisks. Prices are listed where possible for books currently in print. Foreign sources are denoted in curly brackets ({F} French {G} German {I} Italian {J} Japanese/English bilingual). Specific CV's covered are listed in brackets [].
*** in the Index denotes a work by the inventor of the CV indicated. 
%%%   denote individual rulesheets, available from the inventors or from WGR.

Books, Pamphlets, and Individual Magazine Articles
 (Note: all of the works less than 50 pages in length are pamphlets).

Abbott, Robert -- Abbott's New Card Games, 1963, 1968 (paperback), Funk and Wagnalls, no ISBN, $1 plus postage ($1.50 per order) from Abbott  (see address below)     [646]
*Anderson, Gerald Frank -- Are There Any?, 149 pp., 1958
  Classic work on Kriegspiel.
Arnold, Peter, ed. -- The Book of Games, 256 pp., 1985, Exeter, ISBN  0-671-07732-5
  Superb chapters by Fairbairn on shogi and xiang qi (Chinese C). 
d'Autremont, Louis Paul -- Angel Chess, 1933  [25]
Baskerville, H. D. -- Hexagonal Chess, 15 pp., 1929   [51]
Bell, R. C. -- Board and Table Games, 363 pp., paper, 1960, 1969, 1979  (one-volume reprint), Dover, ISBN 0-486-23855-5, $5.00
  Mostly variations from AHC, but a good description of [333].
Boyer, Joseph -- Les Jeux d'Echecs Non Orthodoxes, 100 pp., 1951 {F}
  Along with its 1954 supplement, the standard reference work on CV's, especially modern ones.
Boyer, Joseph -- Nouveax Jeux d'Echecs Interessants, 5 pp., c.1957 {F}
  Hand printed leaflet listing 30 or so additional variants.
Boyer, Joseph -- Nouveax Jeux d'Echecs Non Orthodoxes, 100 pp., 1954 {F}
Brace, Edward R. -- An Illustrated Dictionary of Chess, 320 pp., 1977, Hamlyn, ISBN 1-55521-394-4
  Details on some variants not found elsewhere.
Burroughs, Edgar Rice -- The Chessmen of Mars, 1922
  Science fiction novel introducing the game of Jetan (Martian Chess), described in a two-page appendix.
Capellen, G. -- Zwei Neue Kriegspiele, 1915  [244]
Dawson, T. R. -- Five Classics of Fairy Chess, 145 pp., paper, 1973, Dover, ISBN 0-486-22910-6
  Reprint of series of booklets by the legendary problemist. The fifth booklet includes a description of Raumschach.
Dickins, Anthony -- A Guide to Fairy Chess, 66 pp., paper, 1971, Dover, ISBN 0-486-22687-5
  Emphasizes the problem side of fairy chess. Terribly disorganized but loaded with information, especially on unorthodox pieces.
*Donnelly, Terence -- Hsiang Ch'i, the Chinese Game of Chess, 1974, Wargames Research Group  [676]
Fairbairn, John -- Shogi for Beginners, 166 pp., paper, 1984, Ishi Press, no ISBN, $11.95
  The best introductory book on shogi; complete rules as well as coverage of openings, middle game, and mating attacks, and 16 sample games. The older books by Leggett and Ohara have some minor rules omissions and are less comprehensive in covering strategy.
Foster, Benjamin R. -- Chancellor Chess, or The New Game of Chess, 80 pp., 1889
  Describes [91] as well as some forerunners [62, 82, 531, 588]
Freeman, Jon -- The Playboy Winner's Guide to Board Games, 286 pp., paper, 1979, Playboy Press, ISBN 0-872-16562-0
  The best guide to date on proprietary games; rules and strategy for Ploy and Smess.
Gaige, Jeremy -- Chess Personalia, A Biobibliography, 505 pp., 1987, McFarland, ISBN 0-89950-293-8, $45.00
  Accurate guide to names of inventors, provided they are problemists, authors, or players of note.
Gardner, Martin -- Mathematical Circus, Simon and Schuster; Chapter 15, Problem 2, "Single Check Chess", p.182, 194.
  Discussion of Single Check C and Presto C, including winning strategies for the original form.
Gardner, Martin -- Mathematical Magic Show, Vintage, Chapter 14, "Knights of the Square Table", p. 197ff.  [103]
Gardner, Martin -- New Mathematical Diversions from Scientific American, 1966, Simon and Schuster; Chapter 6, "Board Games".
  Brief descriptions of a number of CV's; full rules for The Maharajah and the Sepoys, including William E. Rudge's 25-move winning strategy.
Godson, William F. H., Jr. -- Three-dimensional Chess, 1931  [263]
Gollon, John -- Chess Variations, Ancient, Regional, and Modern, 233 pp., paper, 1968, ISBN 0-8048-1122-9, Tuttle, $6.25
  Worthwhile guide to historic and regional CV's; nearly useless for modern variants. Rules and sample games for over 30 games. The preface to the paperback edition corrects several errors.
Hagemann, Wally -- CV handout (Nostvention 1988), St. Louis
Hooper, David and Kenneth Whyld -- The Oxford Companion to Chess, 407 pp., 1984, Oxford University Press, ISBN 0-19-217540-8
  Unusual for a chess encyclopedia to treat CV's with such respect; covers a fair number of variants, generally not in much detail (but see [325, 670]). Reviewed in WGR5; now published in paper at $13.25.
Howard, J. T. -- Guide to Double Chess, 8 pp., 1885 [292]
Kister, J., et al. -- Experiments in Chess, Journal of the Association for Computing Machinery, 1957, 4:174-177  [356]
Kluver, Hans -- Doppelzugschach, 31 pp., 1963 {G}  [204]
Kluver, Hans -- Dynamoschach, 26 pp., 1971  {G}  [215]
Kogbetliantz, Ervand George -- Space-Chess, 1952   [332]
Lai, C.K. -- Chinese Chess, An Introduction to the Openings, 65 pp., 1987, C. K. Lai, L4.99 pounds (U.K.)        [676]
Lau, H.T. -- Chinese Chess, 248 pp., 1985, Tuttle, ISBN 0-8048-1495-3, $11.50 (reviewed in WGR8)             [676]
Leggett, Trevor -- Shogi, Japan's Game of Strategy, 100 pp., 1966, ISBN 0-8048-0526-1, Tuttle, $15.95
Marinelli, Filippo -- Triple Chess, 30 pp., 1826
  Translation into English of Marinelli's 1722 work, describing his three-handed variant [634]; also [30].
Maus, Frank -- Cavalry Chess, 13 pp., 1923     [84, 365]
Morehead, Albert; Richard L. Frey; Geoffrey Mott-Smith -- The New Complete Hoyle, 1964, 1991, Doubleday, ISBN 0-385-24962-4, $24.95
  Still the best compendium of rules for games available. Several chess variations [333, 52, 519, 352, 449, 70, 256] are described on pages 609ff.  The brand new revised edition (to be reviewed in WGR11) has deleted three pages of material on Four-Hand Chess and Team Chess.
Morley, F. V. -- My One Contribution to Chess, 1946  [398]
Murray, H. J. R. -- A History of Chess, 900 pp., 1913, Oxford U. Press, reprinted by Benjamin Press, ISBN 0-936-317-01-9, $39.95
Norman, John -- The Players of Gor, 1984, DAW Books, 396 pp., paperback, ISBN 0-87997-914-3
Ohara, Eiroku -- Japanese Chess, The Game of Shogi, 182 pp., 1954, Tuttle
Parton, V. R. -- Challenge & Delight of Chessical & Decimal, 13 pp., 1969
  Describes 14 variants played on the 10 x 10 board.
Parton, V. R. -- Chesshire-Cat-Playeth Looking-Glass Cheessys, 26 pp., c.1970   
  Describes 13 variants, including some of Parton's best. See NA156.
*Parton, V. R. -- Chess Curiouser and Curiouser, 1960
Parton, V. R. -- Chessery for Duffer and Master, 23 pp., 1974
Parton, V. R. -- Chessical Cubism, or Chess in Space, 14 pp., 1970
  Describes 4 multi-dimensional variations. See NA156.
Parton, V. R. -- Enduring Spirit of Dasapada, 19 pp., 1973
  A short history of decimal chess, one of Parton's major interests.
Parton, V. R. -- Idea for a Personal Game, 19 pp., c.1973
  Covers several games based on custodian capture, including (Royal) Scaci Partonici.
Parton, V. R. -- My Game for 2000 A.D. and After, 1972  [642]
Parton, V. R. -- 100 Squares for Chess and Damate, 16 pp., 1971
Parton, V. R. -- "Variations on Chess", New Scientist, May 27, 1965, p. 607.  [12, 147, 310]
Pritchard, David -- Brain Games, 202 pp., paper, 1982, Penguin, ISBN  0-14-00.5682-3   [280, 309, 552, and 676].   He also mentions a Progressive variant in which
Raia, Roman -- Chess as a Wargame, Jagdpanther 6, July 1974, p.4. [105]
Self, Henry J. -- Three-handed Chess and Three-handed Draughts, 1896
*The Shogi Association -- The Great Shogi Games and How to Play Them, 1979, The Shogi Association, write to Hodges for price.
 Covers [171, 172, 367, 598] -- see NA234 and 236 for details. Hodges also sells leaflets on [128, 552, 610, 621, 668] as well as equipment.
Silverman, David -- Your Move, 221 pp., 1971, McGraw-Hill
  Describes [70,258,333,471,569] -- see problems 17-20, 96, 100.
Sloan, Sam -- Chinese Chess for Beginners, 188 pp., paper, 1989, Ishi Press, ISBN 0-923891-11-0, $9.95  (reviewed this issue)
Stone, A. J. -- Chess Variants, 1982 (large pamphlet)
Teruichi, Aono -- Better Moves for Better Shogi, 304 pp., paper, 1983, Kawai Masao, ISBN 4-381-00597-X, $39.95 {J}
Teruichi, Aono -- Guide to Shogi Openings, 214 pp., paper, 1983, Kawai Masao, ISBN 4-381-00598-8, $12.95 {J}
  These two problem collections, translated by John Fairbairn, are  intended to show the player how to think correctly about shogi.   Board notation is Japanese; moves are given in both languages.  Better Moves... includes a 7-page shogi glossary.
Trabue, Isaac H. -- Rules and Directions to Play Four-Handed Trabue, American Chess, 1904   [626]
Verney, Maj. George Hope -- Chess Eccentricities, 196 pp., 1885
  The first CV compendium in English, and the most important before Boyer's books in the 1950's. Covers many variations, particularly multi-player games and other games on enlarged boards.
Wurman, David -- Chinesisches Schach/Koreanisches Schach, 345 pp., paper, 1991, Verlag Harri Deutsch, ISBN 3-8171-1166-5  {G}   (Reviewed this issue)   [676, 92, 532]

Abbreviations used in index references:           
AHC  -- Murray   CVARM -- Gollon    MGTA -- Parton (8)
AJS  -- Stone    ESD  -- Parton (6)  MMS  -- Gardner (2)
CCCS -- Parton (5) GFC  -- Dickins   NCH  -- Morehead
CCP  -- Parton (2) GSG  -- Shogi Assn. NJEI -- Boyer (2)
CDCD -- Parton (1) HSCD -- Parton (9)  NJENO -- Boyer (3)
CDM  -- Parton (4) IDC  -- Brace    NMDSA -- Gardner (3)
CE  -- Verney   IPG  -- Parton (7)  OCC  -- Hooper & Whyld
ChCh -- Foster   JENO -- Boyer (1)  SA  -- Shogi Assn. leaflets
CVARM -- Gollon   MCi  -- Gardner (1) TCh  -- Marinelli

Periodicals

BCM British Chess Magazine
  Volume 104 (Jul84), p318 has a Pocket Knight game between Buckley and Richardson.  Many variants from the early 20th century can be found in older issues.
CA  Chess Amateur
C   Chessics           G. P. Jelliss
CL  Chess Life (and Review)
CS  Chess Spectrum Newsletter  Anthony V. Paletta
  The two 8 page issues of thie newsletter, published in 1980, include rules for dozens of variants. Paletta does not credit inventors (including himself), so I am guessing at which variants are his own.   Descriptions of several well-known variants are wrong (due either to errors or Paletta's changes to suit himself); in most of these cases I do not list CS as a reference.
CCJ Circle Chess Journal     Alphonso F. Stanonis  1963-1977
CR  Conquest Review       Donald Benge
ES  EteroScacco         Alessandro Castelli   {I}     Regular coverage of [256, 309, 371]; also [40, 76, 473, 474, 476]
ESP EteroScacco Problemi     Alessandro Castelli   {I}
FCR Fairy Chess Review      T. R. Dawson
FS  Feenschach
GR  The Gamer
G   Games            Will Shortz         Back in publication (see Game News)  [96, 230, 265, 267, 552, 621]
G&P Games & Puzzles       David Pritchard
GPJ The Games & Puzzles Journal G. P. Jelliss
J'A J'Adoube           David Moeser
NA  Nost-Algia          Bob Lauzon, Les Roselle
RMM Recreational Mathematics Magazine
SC  Schema     Michael Waitsman    Published only two issues in 1981, 20 and 32 pp.; number 1 covered Pre-Chess (there called Meta-Chess) "The Next Stage in the Evolution of Chess".
SH  Shogi         George Hodges, The Shogi Association Ltd.
SW  Shogi World
TC  Transcendental Chess     Max Lawrence (TC/Lawrence)
VC  Variant Chess        G. P. Jelliss
WGR                      Michael Keller
YFC Ye Faerie Chessman (The Gamesman)  Donald L. Miller


Addresses
N.B.: Many of the commercial variants in this issue were published many years ago (check the dates given), and are likely out of print (and the companies out of business). Therefore many addresses below may be out-of-date, but are given for the sake of completeness.
(As this was published in 1994, it is reasonable to assume that by now nearly every address is out of date)

Robert Abbott, 33 Gold Street, #527, New York, NY 10038
AISE, c/o Direttore Alessandro Castelli, via Potenza 11, I-62010 Villa Potenza (MC) Italy
Mirko Babic, Zagrebacka 47, 41320 Kutina, Yugoslavia
Donald Benge, 1122 W. Burbank Blvd., Burbank, CA 91506
Benjamin Press, P.O. Box 112, Northampton, MA 01061, tel. (413) 584-0374
Bradspelaren, Bengt Ericson, Smalandsgatan 20, 615 00 Valdemarsviu, S-Sweden
California Chinese Chess Association, 711 Fair Oaks, Suite F201, S. Pasadena, CA 91030
Carter Hall, 6 West 32nd Street, New York, NY 10001
Chance Chess Company, P.O. Box 802, Hillsdale, MI 49242
Chess Too, Box 229, 1552 Hertel Avenue, Buffalo, NY 14216-2882   (advertised in Chess Life, including board diagram, but company did not respond to inquiries or orders)
The Choiss Game Corporation, Suite 509, 720 Spadina Avenue, Toronto, Ontario M5S 2T9, Canada
Cleveland Public Library, John G. White Collection, 325 Superior Ave., Cleveland, OH 44114-1271
Philip M. Cohen, 112 Oak Lane, West Chester, PA 19382
George R. Dekle, Sr., Rt. 12, Box 451-B, Lake City, FL 32055
Difft, Inc., P.O. Box 3735, Shawnee, OK 74802
Dover Publications, Inc., 31 East 2nd Street, Mineola, NY 11501
Eagle Tree Software, P.O. Box 164, Hopewell, VA 23860,  (804) 452-0623
Fouray Plus, 710 Silver Spur Road, #322, Rolling Hills Estates, CA 90274
Games Magazine, (editor) 19 W. 21st St., New York, NY 10010; (publisher) B & P Publishing Co., 2000 Commonwealth Ave., Auburndale, MA 02166   (subs) Games, One Games Place, P.O. Box 55481, Boulder, CO 80322-5481
Halcyon, 3321 64th Avenue, Cheverly, MD 20785
Hexagonal Chess Publications, 32 Rosedene Ave., London SW16 2LT, England
HEXChess, Inc., P.O. Box 53, Boston, MA 02162
George F. Hodges, P.O. Box 77, Bromley, Kent BR1 2WT, England
Horizon Games, Inc., P.O. Box 701, Plainfield, IN 46168
Malcolm Horne, 10B Windsor Square, Exmouth EX8 1JU Devon, England
Hypergames Company, P.O. Box 3026, Richmond, VA 23235
International Chess Company, P.O. Box 4152, Great Neck, NY 11027
Interplay Productions, 3710 S. Susan, Suite 100, Santa Ana, CA 92704, telephone (714) 549-2411
Ishi Press International, 76 Bonaventura Drive, San Jose, CA 95134   telephone (408) 944-9900
G. P. Jelliss, 99 Bohemia Road, St-Leonards-on-Sea, TN37 6RJ, England
JET Software, Box 144462, Miami, FL 33114-4462
C.K. Lai, 12 Lagan House, Sumner Road, London, SE15 5RB, England
Leong Jacobs, Inc., 2729 Lury Lane, Annapolis, MD 21401-7312
Mattel Toys, 5150 Rosencrans Avenue, Hawthorne, CA 90250
McFarland, Box 611, Jefferson, NC 28640
Modern American Chess, 84 Main Street, Hackensack, NJ 07601
David Moeser, P.O. Box 30072, Cincinnati, OH 45230
NOST, c/o Les Roselle, 111 Amber Street, Buffalo, NY 14220-1861
Original Toy Corporation, 86 Thirty-Fourth St., Brooklyn, NY 11232
Pacific Game Company, North Hollywood, CA 91605
Parker Brothers, 50 Dunham Road, Beverly, MA 01915
Port Kar Industries, 19644 South Falcon, Oregon City, OR 97045
David Pritchard, Badgers Wood, Hascombe Road, Munstead, Godalming, Surrey GU8 4AA England
R. Wayne Schmittberger, 17 Beechcroft Drive, East Windsor, NJ 08520
Tiziano Sala, via Einstein 136, 41100 Modena, Italy
SDM, Inc., Box 9696, Baltimore, MD 21237
Super Chess, Inc., P.O. Box 83, Oakland Gardens, NY 11364
3M Corporation, Minnesota Mining and Manuf. Corp., St. Paul, MN 55101
Taurus Games, 3600 W. Villard Avenue, Milwaukee, WI 53209
TC/Lawrence 1502, 1655A Flatbush Avenue, Brooklyn, NY 11210
Think Tank Games, P.O. Box 534, Harrisonville, MO 64701
D. F. Thomson Co., P.O. Box 909, Wilmington, VT 05363-0909
Tri-Chess, Inc., 7, Cedar Grove, Greetland, Halifax, HX4 8HT, England
Trigame Enterprises, Inc., P.O. Box 1055, Woodbridge, NJ, 07095
Charles E. Tuttle Company, 28 South Main Street, P.O. Box 410, Rutland, VT 05702-0410, tel. (802) 773-8930
UK Chinese Chess Association, C.K. Lai, General Secretary, 12 Lagan House, Sumner Road, London, SE15 5RB, England
U.S. Chess Federation, 186 Route 9W, New Windsor, NY 12553-7698
Variant Chess, 99 Bohemia Road, St-Leonards-On-Sea, TN37 6RJ, England
Vegas Fun Chess, P.O. Box 85087, Las Vegas, NV 89185-0087
Verlag Harri Deutsch, Grafstrasse 47, D-6000 Frankfurt/Main 90, Germany
Vietnamese American Chess Assn., P.O.Box 1839, Springfield, VA 22151
The Wickett Works, P.O. Box 24, Natrona Heights, PA 15065


Alphabetical Index
   This list contains the names of chess variations in alphabetical order, ignoring all spaces and punctuation. E.g. Warrior Chess precedes Wa Shogi. Numbers are alphabetized as if spelled out; the abbreviation C as if spelled out Chess. Listed with each game are (where known):
(1) the inventor (a code of two or three lowercase initials -- the middle letter may be a middle initial, second letter of first name, or other letter given to eliminate ambiguity).
(2) the year of invention or publication (two digits denote 20th century; multiple dates are revised versions; the date may be excluded if it is clear from the source). Month of publication (where available) is abbreviated by a single letter: January, February, March, April, maY,  jUne, juLy, auGust, September, oCtober, November, December.
(3) bibliographic sources (for CV's with many references, the most useful
  are given). The prefix "r." denotes a review; "a." an advertisement.
(4) array (if unorthodox) and rule changes (see Additional Rules). For some complex games, board size is given, followed by number of units per side and number of species (initial, promoted, total).
(5) cross-references to related games (indicated by numbers in brackets []). Numbers enclosed in curly brackets {} indicate sample games.
(6) classification code (the C is omitted) and page references outside   the Panorama.  A capital letter indicates complete rules for play are given in the Index and/or the Panorama (this may assume knowledge of common variants such as Kriegspiel, shogi, Ultima, or xiang qi).

MxN:ABCDEF... is a shorthand Forsyth used for semi-orthodox games played on a rectangular board of M files and N ranks, with pieces along both players' first ranks and pawns along both second ranks. ABCDEF... is a list of white's pieces from left to right. Black's pieces are the mirror image (i.e. kings are on the same file), unless the symbol <> appears, which indicates that Black's pieces are arranged in the same order left-to-right from her point of view as White's. If a number in brackets follows the board size, the game uses the same array as the cross-referenced CV (note the choice of arrays in [174] and [177]).
[] denotes an optional part of a name (e.g. Berolina Chess is also known as Berolina Pawn Chess).
() denotes an alternate name -- this may be a variant close to the original in alphabetical order (e.g. Berolina Grid can be shortened to Berogrid) which is omitted to save space, or an important alternate name (Shogi = Japanese Chess).
== means that the entry is an alternative name; following is the standard name.  Not every alternate name is included -- try the reverse for a combination name (Giveaway Knight Relay), or the inventors list for an alternate name including an inventor's name (Piacenza's C). Most foreign names have been translated, but a few well-known ones are included as variant names.
==> indicates that the game is a slight variation of another entry (an alternate array or a minor rule difference).
1HO denotes a  variant which was played in the First Heterochess Olympics.
NV denotes a variant played at an annual NOSTvention tournament.
   I have tried to eliminate duplicate names as much as possible, but a few were unavoidable. The manufacturers of commercially published variants are listed in boldface. Some CV's combining two variants are listed, when sample games or added rules are referenced. Generally one can infer the rules to a combination game by looking up the individual components; exceptions are noted in the Panorama. Some games have only general descriptions due to lack of space or incomplete information.

 1 Absolute Checkless C  rp  C2                   X5
 2 Absolute Rettah C  vrp NJENO NA182   >>183           E
 3 Absorption C  NA170,224,227,280  NJENO              W1
 4 Acedrex de Los Quatros Tiempos   NA306 CVARM  AHC        y2
 5 Actuated Revolving Center (Arc) C aef,whr 38 NA111 FCR 2/37   M1
   C2,12  R(de45)cIU
 6 Actuated Revolving Grid C jjs NA168 C3,12 R(ab12,...gh78)cIU   M1
 7 Actuated Revolving Quarterboard C  phj C12            M1
   R(ad14,eh14,ad58,eh58)cIU
 8 Advance C   CS1  $$/8/p(8)/16/P(8)/8/$  E1           A1
 9 Advancing Duffery  vrp  CDM   $$/8/p(8)/16/P(8)/8/$ E1    X6
10 Airplane C  rws NA256  A=Airplane                G5
   10x10:racbqkbxar/ppppnnpppp/4pp4/40/... C3,E5,P=+ACX,V1
11 Alfonso's Spanish C  AHC                      c1
12 Alice C  vrp 54  CDM NA96,97,100,164,165,171,174,180,182,197,  I2
   216,227,228,231,247,257,262,296 NJENO OCC C2  New Scientist
13 Alice Rotofile C  dm 70 J'A                   m1
14 All-Angle C dm,jag 71 J'A                    j1
15 All-Connect C  jeb 90   %%%                  o2
16 Alliance C avp  CS1                        x4
17 All-in C  cmt  C1,3  AJS [Free-for-all C]            R1
18 All Mate C  cmt  90  VC2                    u6
  All The King's Men == Smess   Parker Brothers
19 Almost C rb NA205,206 8x8:RNBXKBNR                F1
20 Amazon C  tl 1891 BCM,F91  NJENO  8x8:RNBAKBNR         F1
21 Amazon Queen  wh 88 8x8:NNNAKNNN  ***  >>331          F1
22 Ambi-Chess vrp CDCD(10x10:RNKQBBQKNR)  ES53           X4
   HSCD(10x10:RNKQBBQKNR/10/p(10)/40/...)
23 Ambition C  rb NA214,218,222,227 ES53              B5
24 Ambivalent Knight Relay  jos NA166,169              Q1
  Anchor-Ring C  == Toroidal C
25 Angel C lpa 15 *** BCM,Y34 NJENO IDC 9x8:RNBQKABNR <> C23,P=A F1
26 Angular Four-Handed C  vrp  NJENO                 y2
27 An-nan C  mh  NA218  C4  AJS                  Q1
28 Antipodean C  gpj 76  C1,2,10                  V2
29 Anywhere C  NA325                         Q2
  ARC Chess == Actuated Revolving Center C
30 Arch C  1683 fp  Marinelli ESD  10x10:RNBFQKSqBNR       g1
31 Archbishop C  dh  NA112  10x8:RNBAQKABNR  A=Archbishop    G2
32 Archer C  avp CS2 7x7:RNAKANR  A=Archer (E+W)         H2
   5x9:rnknr/1a1a1/p(5)/15/....
33 Archimedes C  pmc  NA227                     u6
  ARG/Q Chess == Actuated Revolving Grid/Quarterboard C
34 Arrow Pawn C  rap 38 NA112,190                  D1
35 Atomic C  nbt 49  JENO  IDC                   g5
36 Auction TC  ml   TC                      b1
37 Auto-Additive C  cmt  C17                    P2
38 Automatic Rifle (Autorifle) C  rb NA204,205,211          U2
39 Autosuction C  rb NA238                      V2
40 Avalanche C rb 77 NA214,216,218,233,235,238,246,247,252,256,262, R1
   263,286,296,300,302,304,306-308,314,316,324,325  WGR2-4
   ES29-31,34,35,40,41,44,45,47,48,52 1HO NV'79,85,87,89
41 Aviation C ll 13 CA,F22 JENO                  G5
42 Baby C  ro 73 4x8:rqkr/nppb/pbnp/8/...   C1/-,E2n       H2
43 Balanced Avalanche  rok NA324                  R1
  Balanced Equidistant C  == Equidistant C
44 Balanced Marseillais C rbb 63 NJEI NA36,94,180,312,321 ES50 {1} N1
45 Balanced Multimove C mk WGR7                   N1
46 Bankhouse C dm 71 J'A                      V1
47 Bank of Scotland [-- Main Branch]  brt 76 NA192 ES49,53     N3
48 Bank of Scotland -- Modern Branch brt 76 NA192          N3
  Baroque  ==> Ultima
49 Barrier C   C11  AJS                       O2
50 Baseline C   OCC [Randomized C] IDC               B1
51 Baskerville C  hdb 29 ***  NJENO                k1
52 Battle (Battlefield) C  NCH JENO  CVARM             B1
  Battu-Battant == Giveaway C
53 Berolina [Pawn] C en 26 NA77,112,127,152,178,188,198,213,214,  D1
   245,305 OCC NJENO GFC  Funkschach 15G26
54 Berolina Grid (Berogrid) C  NA112,229,250    >>269       D1
55 Best Decimal Butter  vrp NA150,182 CDCD 10x10:RRNBQKBNRR E3n  U4
56 Betza's Unequal Armies  rb NA247,248,251,252,254,255,256,258   a2
57 Bicapture C  rob  NA169  NJEI  8x8:RQBNKBNR          X5
58 Bicolor C  ga  NA169 NJEI  8x8:RQBNKBNR             X5
59 Biflux C  rb 74  NA177                      W1
60 Billiards C  jb 54,57 NA193,194,253 NJENO NJEI CS1 ES51   J3
61 Biplace C  bdb     NA150  NJEI               P1
62 Bird's C heb 1874   10x8:RNBXQKCBNR  X>Guard C>Equerry    F1
63 Bishop Relay C  mc NA183                     Q1
64 Blizzard C  rb 77 NA214,218                   B4
65 Blood Brother C  rws,pmc NA247                  T2
66 Bogart's Ultima  kb 85  8x8:ILAKWXGC <>             U7
67 Bouncy C  pn, pd  VC3                      J3
68 Brownian Motion C  rb NA168                    m1
69 Bruce's Billiards C  rbb 65  8x7 E1               J3
70 Bughouse C jec  40  NA150,170 JENO C13 YM NCH        V2
71 Burmese C  NJENO  AHC  CVARM  NA240              c4
72 Butters  vrp CCP NA182                      U4
73 Buzzard C  rb 77  NA214,218                   b4
74 Byzantine C   CVARM [Round C]  4x16 rings            j2
75 Camelot C  wh 88  8x12   ***                 j3
76 Cannibal C (Progressive Absorption)  NA227,280   ES31,39,41,44,46,48,50,52          W1
77 Capablanca's C jrc 29 NA168,178 ES51 CVARM 10x8:RNCBQKBXNR P=+XC F1
78 Capablanca's Decimal C  jrc 28 NJENO HSCD ES51         F1
   10x10:RNBCQKXBNR E3,P=+XC
79 Capricorn C  vrp NA182  CCP                   U4
80 Capturing Duffery  vrp  CDM                   X6
81 Cards C  NA322 ES53                       O3
82 Carrera's C pc 1617  CS2 CE ChCh  10x8:RCNBKQBNXR P=+CX   F1
83 Cassandra C  rb NA168                       U6
84 Cavalry C  fgm 23 *** CA,F25 JENO               F1
85 CCC Chess  rb NA172                        G3
86 Centaur Royal C vrp (CDCD,ESD)10x10:5n4/rrbbqqbbrr/p(10)/40/...<> E
   (HSCD)10x10:rrbbqqbbrr/n8n/p(10)/40/... N>Centaur Royal  C-
87 Centerless C avp CS1  $$/ppp2ppp/8/3--3/3--3/8/PPP2PPP/$    H3
88 Century C  brt  10x10:RNBQAKQBNR  N = N + Z  E5        F1
89 Chameleon Circe  mo    VC1 VC7                V4
90 Chance C  82 NA292 a.CL40:12(D85)p41 The Chance Chess Company  o3
91 Chancellor C brf 1887 St. Louis Globe-Democrat 12F1887 ChCh   F1
   NJENO 9x9:RNBQKXNBR
92 Changgi   Wurman  CVARM  AHC                  c4
93 Chator  CVARM;AHC [Malay C]                    c4
94 Chatrang  NA303  AHC                       c1
95 Chatty C  igr     VC1                     y2
96 Chaturaja  NA304,305 CVARM  JENO  G21(J81) [Chaturanga]    c1
97 Chaturanga NA301 AHC CVARM 8x8:RNEFKENR <> Ca,E1,P==| (also ==96) C1
98 Checker C  grd 86   %%%                     g4
99 Checkers C  hm 74 J'A                      O2
100 Check Force  brt  NA202                     X5
101 Checkless C  OCC C2 NJENO  YFC7 IDC CS1 [Prohibition C]   X5
102 Cheshire Cat C vrp NA156,244 CCP VC1 [Haaner C]        M2
   10x10:RRNBQKBNRR
103 Cheskers swg 47 NA168,220 MMS CS1 ES39  JRM 3:130-138(L68)  G4
   1m1k1k1b/p1p1p1p1/1p1p1p1p/16/P1P1P1P1/1P1P1P1P/B1K1K1M1 P=KBM 
104 Chesquerque  grd  86  %%%                   l2
105 Chess as a Wargame  rmr ***                   n2
106 Chess A vs. Chess B  rb NA209                  a2
107 Chess Draughts hr 1883 CE       P=B           G4
   1p1q1b1p/p1p1p1p1/32/1P1P1P1P/P1B1Q1P1
108 Chessenat rb  NA164  $$/p(8)/w(8)/16/... w>Kelb        U3
109 Chessers fgm 25 CA,Y25 NA191  NJENO (also == [457])     P2
110 Chessgi rb 64 NA167,188,215,218,230,243,254,260,284,288-292,  V1
   295,296,308,324,325  1HO  ES49,51,52
111 Chess in Disguise  jdb C4,8,10                 B3
112 Chess in the Round  72  NA168  Saxon Agencies Ltd.       j2
113 Chess in the Third Dimension   NA205   Nypro Co.        i1
114 Chessnik  a.CL41:1(J86)p67   Difft, Inc.            k1
115 Chessnuts  85  r.WGR7    W2    Halcyon           y2
116 Chess-O-Rama lhn 73 IDC                     y3
117 Chess To Go  ep 88                        D2
118 Chess Too  ad.CL42:12(D87)p47  Chess Too            h3
119 Chess Tweedle vrp 52 NA182 CDCD CDM NJENO,Chess Y52 [Twin Orthodox C]  C-/2,E3n (var: E6)     X4
   10x10:RNBKQQKBNR
120 Chess II  brt 75,86  NA194  %%%  Z=Z+N  E5/E6        F1
   12x12:rxbcqakqcbxr/ppznppppnzpp/p(12)/72/...
121 Chess with Japanese Captives rbb                 V1
122 Chess with Reserves  es 51  NJEI                B2
123 Chi Chi's C cch Eye N68 NA105-108,111,168            H2
   8x4:$$/p1ppp2p/P1PPP2P/$
124 Chimaera C vrp NA182 CDCD HSCD  10x10:RNCBQKBCNR E3n,P=+Ch  V2
   (pmc) 8x8:rcbqkbcr/2n2n2/p(8)/16/... E1  C=Chimaera
125 Chimaerine C  vrp CDCD                      V2
  Chinese C == Xiang Qi        
126 Choice C   brt   %%%                      O1
127 Choiss  87 NA310 r.G98(U89)  The Choiss Game Corporation    m2
128 Chu (Middle) Shogi NA230,233,247 AHC CVARM SA 12x12/46/21,20,30 c3
129 CIF (Chess In Friendship) Four-Handed C  NA282  N4a,Q1,W3    y2
  Circean C  == Gryphon C
130 Circe C  pm,jpb  67  OCC IDC  NA197,262  C2,6,8  GPJ4    V2
131 Circe Malefique  GPJ10                      V2
132 Circle C  afs  63  NA177  CCJ                 k3
133 Circular C ghv JENO  N2 4x16, N3 4x24, N4 4x32         j2
  Circum Morus == Jabberwocky C
134 Citadel 40  Parker Brothers                   a1
135 Citadel Zatrikion                         j2
136 Citizen C  avp  CS1                       N2
137 Co-Capture C  rb 74 NA169,231,263                U1
  Co-Chess (Coordinate C) rb NA229,231,232  ES50
   >>39,137,140,149,189,210,209,410,424,434,469,483,520,587,628,652
138 Cohen's Array  82 pmc  NA263 8/$$/p(8)/16/P(8)/$/8 C-,E1   A1
139 Cohen's Error C  pmc NA210,213,214,217             G3
140 Co-Immobilization C  rb  NA169                 V3
141 Coin C  gia  ES48                        R2
142 Columbia Cannon C rb 73  NA164,168,172,179,209,213 <>     G3
143 Columbia Cannon Transchess rb NA181               V2
144 Combinating C  wsc 1898  BCM,L98  NJENO            P2
  Complete C  == Shatranj Kamil
145 Compromise C  fg  NA96,157,188,220,233,262 NJEI VC1,2 ES49  O1
  Compulsion C  == Must-Capture C
146 Confederate C  fgm 25  NJENO                  P2
  Conquest C == Quest-Chess      
147 Contramatic C  vrp  New Scientist                x5
148 Conversion Bughouse C  job 51  JENO               V1
149 Conversion C  rb 73  NA161,165,167,170,171,181,195,197,200,208, V1
   225,229,249,263  ES50
150 Conversion Circe C  llt  1840  JENO               V1
151 Coordinator C  grd 86 %%% 10x10:RNCBQKBCNR <> C=Coordinator  U1
152 Co-Regal C vrp  CCP NA174,175,188,189,191,229,236,238,260    X4
153 Co-Regal Knight Relay C   NA188-191               Q1
154 Corner C  avp  CS1  kbp2pbq/nrp2prn/pp4pp/16/... <> C-,E1   D1
155 Corner-wrap C rb  NA253                     j1
156 Coronation C  fgm 25 NJENO                   P2
157 Corridor C avp CS1 1nrqkrn1/2b2b2/1p(6)1/16/...  C-,E1 >>293 A1
158 Courier C OCC NA295 CVARM AHC ES53 12x8:RNEBVKFWBENR C-,E1,P=F C2
159 Covert C  88  JET Software                    s2
160 Crescendo C  72 Strato-Various Products             p2
161 Crompton's C  gec 60                       y2
162 Cross C   a.G83 (J87)  Cross Chess International Pty., Ltd.  h3
163 Cross C  grd  82   %%%                     k1
164 Crossings C  pmc 73 NA167,183                  Q3
165 Cubic C  vrp NA156 CCCS                     I1
   6x6x6:144//p(6)/24/p(6)//rnubqk/p(6)/12/P(6)/KQBUNR
166 Cubic C  vp 77,87  VC2  7x7                  b5
167 Custodian C  grd  86  %%%                   U3
168 Cyclic Progressive C  rc ES30,35                N3
169 Cylinder C c.25 NA79,81,156,230,253,254,266 JENO CS1 C2 IDC  J1
170 Dabbabante C  vrp  HSCD  10x10:RNDBQKBDNR           G1
171 Dai-Dai Shogi  GSG  17x17/96                   c3
172 Dai Shogi    GSG  15x15/65                   c3
173 Damate  vrp  HSCD (10x10:RBNQKKQBNR), CDCD (10x10:PBRQKKQRBP)  G4
   NA189,191 [Chess-Checkers]                   
174 Damatic C  vrp  HSCD  10x10:[78,179,546]            G4
175 Dawson's 4-D Chess  tdr 26  CA,D26  JENO  4x4x4x4       i3
176 Deal C  JENO                           A2
177 Decimal Butter C  vrp HSCD  10x10:[78,119,179,675]       U4
178 Decimal Duffer's C  vrp  HSCD                  X6
179 Decimal Falcon-Hunter C  ks CDCD ESD HSCD NJENO        G2
   10x10:RNBHuQKFaBNR  C3,E3n,N=N{Z}
180 Decimal Imitante Queen C  vrp  HSCD  10x10:RNIBQKBINR     T1
181 Decimal Oriental C  vrp  HSCD                  G3
   10x10:rcmefkemcr/2n4n2/pp1pppp1pp/40/...  c=Korean Cannon
182 Decimal Scaci Partonici vrp 10/p(10)/prbqnnkbrp/40/... (CCP)   U3
   10(or 2p(6)2)/prnbqkbnrp/prnbqkbnrp/40/... (HSCD)
183 Decimal Rettah C vrp 52 NA182 NJENO FCR8:7:53(D52) FS p130  E
   10x10:RNBQKKQBNR (FCR/FS), NBKQRRQKBN (NJENO/FS), RNKBQQBKNR (FS)
   C-,E3n,P=+K
184 Dekle's Chessgi  grd 86 NA294  %%%               V1
185 Dekle's Nightrider C  grd 86  %%%  9x9:XNrCQKQCNrX       F1
186 Dekle's Space C  grd 87  %%%                  i1
187 Demigorgons vrp NA156 CCP  D=demigorgon            V3
   rnbddbnr/4qk4/p(8)/16/P(8)/4QK4/RNBDDBNR
188 Demotion Bughouse  vrp  NJEI                  V4
189 Demotion C  rb 73  NA229                    V4
190 Dense C  rg 65 YFC7                       h4
191 Deployment C  GR5 NA263  AJS [Hidden C]             b2
192 De Vasa's C  hev  NJENO 9x8:RNBQBKBNR <>            K1
  DG Chess  == Displaced Grid C                   
193 Diagonal C  ll 13 JENO                     A1
   knbrp3/bqpp4/npp5/rp1p3P/p3P1PR/5PPN/4PPQB/3PRBNK
194 Diamond C  pr 1886  BCM,M86 NJENO     >>345       A1
   krbp4/rqnp4/nbpp4/pppp4/4PPPP/4PPBN/4PNQR/4PBRK
195 Dice C JENO IDC  (also generic for Co3)             O3
196 Displaced Grid (DG) Chess dg NA168                L1
  Displacement C  == Reversed King and Queen
197 Dodo C  vrp CCP  48/RNB2nbr/KBN2nbk  >>496         X6
198 Domino C  avp  CS2                        L2
199 Double Avalanche C  rb                      R1
200 Double Bughouse C    NA174,247              Y4
  Double C  == generic name for four-handed chess 
201 Double Conversion C rb NA161                   W2
202 Double-King C  dm 70,79,88  J'A NA244 CS2           X3
   10x8:RNBKQSKBNR  P=+S  C4/2 (either king) S=squirk (70=Sq)
   (1988) 8x10:----kk----/rnbqsbnr/p(8)/32/P(8)/RNBQSBNR/----KK----
203 Double Lazy Susan C  brt  %%%  R(cf36)cP(de45)aP       M1
204 Doublemove C fg 57 NA160-161,163-165,190 ES49,53 NJEI Kluver(1) N1
205 Doublemove Dynamo NA151,164,167[D.D.Shatranj],180,300       U5
206 Double Option C                          O1
207 Double Queen C  maj J'A 71                   A1
208 Double Rettah C vrp CDM NA182,183 2rnbpqk/2rnbpqk/2p(6)/6pp/  X4
   PP6/P(6)2/KQPBNR2/KQPBNR2 P=QRBN C-,E1
209 Double Reversion Conversion C  rb 73 NA161,181         W2
210 Dunsany's C ld 42  JENO    p(32)/24/$  E1         A2
211 Duo C   AJS                           i2
212 Duperchess js 72  J'A                      P1
  Dutch Billiards C == Pocket Billiards C
213 Dutchess  ah 82 NA264                      b1
214 Dying Zombie C  pmc  NA175                   W2
215 Dynamo C pk,hk 68 *** NA147,148,151,152,164,192,199,208,217,224, U5
   226,228,230,232,236,243,244,256,297,300,303,304 ES49,50,52 {2}
216 Ecila C  vrp NA156  CCCS                    i3
217 Eight-handed C  ghv 1884  JENO                 y3
218 Eight Pawns and Two c.1500 CA,S10 NA37 NJENO GFC AHC     A2
   $$/p(8)/32/P(8)/4K3
219 Emperor King C  rws  83                     E
220 The Emperor's Game  llt 1840 CE 10x10:RNBAKQCBNR E3,C4/3   F1
221 Empress C  fgm 25  JENO NJENO                 P2
222 English Progressive C NA282,307-310,325 ES49,50,53 AJS NV'88 {3} N3
223 En Passant C  rb 73  NA217                   T2
224 Equidistant C  job  NA150  NJEI                O1
  Eradication C  == Co-Capture C
225 Escalation C  gpj  73  GPJ7                  w1
226 European Four-handed C 1784 JENO  C-,E1,M2*46,O1,Q1,W3     y2
227 Exchange C  AJS                         y4
228 Exchanger C avp  CS1                       Q1
229 Exotic C rws 84  %%%  >>390,608                q5
230 Extinction C  rws  G66(G85) [Survival of the Species]      X3
   NA298,299,301-304,312,316 ES38,49  NV'86 {4}
231 Falcon-Hunter C  ks 43 JENO NJENO NJEI            G2
232 Falcon-Hunter Chessgi  grd 87  %%%               g2
233 Fast Track C pmc 86 NA299                    D2
234 Fishaway (Giveaway Lumberjack) mer 75  J'A           L2
235 Fish C dm 71  J'A   CL44:11(N89)p42              D1
236 Five Rider C  trd 36  C2                    D2
237 Fortress C  ll  13  JENO  CA,J22                H3
   8x10:2pppp2/$$/2pppp2/--4--/--4--/--4--/--4--/2PPPP2/$/2PPPP2
238 Fouray  jq 86  r.(p.14) Fouray Plus              y2
239 Fourfold Way C  pmc 74  NA171                 p2
  Four-handed C == generic name for Cy2  NCH CVARM [Double C]
240 Four Knights C  8x8:RNNQKNNR  P=NRQ  CS1 [Double Knight C]   A1
241 Four Seasons C rb 77   (also == [4])             B4
242 Four-Way C  srs 87  r.(p.14)   Taurus Games         y2
243 Frankfurt C  56  FS4p265                     W1
244 Free C  gc 15 ***  (also == Free Placement C)         L2
245 Free Choice C  brg 85  WGR6                   b6
  Free-for-all C  == All-in C
246 Free Opening C  pf 26  NJENO  B3,C-              B2
247 Free Placement C  es  NJEI NA240  C-             B1
248 Free Rotation C  pmc NA111  R(*2x2)eIU             M1
  French Billiards C  == Billiards C
249 Frontier C  avp  CS1                       L2
250 Game of Pawns   4k3/p(8)/32/P(8)/4K3  NJENO          A1
251 The Game of War  fim  1770  YFC8  CE    >>479       D1
    11x11:4rkr4/rbbnqrqnbbr/w(11)/... w=w[f]
252 Generalized C  rws  %%%   WGR6                 b6
253 Genie C 1827  JENO CE                      B5
254 Ghost C trd 19 C13,15 NJENO YFC7 (also == Bughouse, Kriegspiel) W2
255 Ghostrider C  rb 78 NA216                    S2
256 Giveaway (Losing) C  NA127,153,166,169,172,179,181,184,187,190,  X2
   191,198,208,233,236,249,294,297,312,318 JENO [Battu-Battant]
   NCH  ES [Vinciperdi] 1HO GFC OCC G&P62,63 CS1 [Losing C] 
257 Giveaway Circe  mb  85  ESP2                  V2
258 Giveaway Robado  JENO YM                     X2
259 Global C  65  Original Toy Corporation              j2
260 Global C  85  International Chess Company            j2
261 Gnight Relay C  rb                        Q1
262 Godneff's C  JENO                         y3
   8x24:$$/p(8)/32/P(8)/$/$/P(8)/32/p(8)/$$/$$/p(8)/32/P(8)/$
263 Godson 3-D Chess  wfg 31 ***  8x8x8              I1
264 Gorgona C vrp CDCD HSCD ESD NA133   >>187         V3
   10x10:RNDBQKBDNR D=demigorgon
265 Grand C  cf  86  G83(Jan87) NA299,313              f1
266 Grande Acedrex CE CVARM                     c2
267 Grasshopper C  job  NA309 G76(U86)p52 NJEI          G3
   $$/g(8)/p(8)/16/P(8)/G(8)/$ E1,P=+G
  Great Chess  == generic name for Ch1
268 Gregarious C  brt    %%%                    P1
269 Grid C ws 53 NA97,168,178,191,197,199,201,205,206,217,222,227  L1
    CS1 VC5 C2,3 NJEI
  Gridolina == Berolina Grid C
270 Griffith's C  atg  CA,S08  NJENO                B1
271 Gryphon C  vrp  CDM  HSCD [Circean]              b5
  Guarded C == Icelandic C     
272 Gumption C  JENO                         R1
  Haaner C == Cheshire Cat C
273 Half-Board Alice C vrp NA182 NJENO 4x8:rqkr/nbbn/pppp/8/... E1 I2
  Half-Queen's C == Semi-Queen C
274 Halma C  grd 86  %%%   V3                  q5
275 Hayward's Double C jgh 27 NJENO 16x12:$$,$$/p(16)/128/... E4  x4
276 Head's 4-handed C  wgh  1834  NJENO  12x12          y2
277 Heian Dai Shogi  13x13/34/13,2,14                 c3
278 Helpmate C  mmm  JENO IDC [Double-Move]  (also == Refusal C)  R1
279 Hexachess dm                           k1
280 Hexagonal C wg 49,53 NA191 OCC Pritchard G&P23,25 NJENO   k1
   Hexagonal Chess Publications 
281 Hexagram C avp  CS2  96 diamond cells              k3
282 Hexchess avp  CS2                        k1
283 HEXChess   HEXChess, Inc.                    k1
284 Hexshogi  grd  %%%                       k1
285 Hexstar C avp  CS2   54 diamond cells             k3
  Hidden C  == Deployment C                    
286 Highcastle C ep 88  NA307,308,322  {5}            Q4
287 High-Low C  rb NA211                       x6
288 Hindustani C   AHC                       c4
289 Hobbler C  avp  CS1                       O2
290 Hopscotch C alp 80 Hopscotch 1 (S80) ES45   B123,C-     B1
291 Horizontal Cylinder C  (mk):p(8)/$$/p(8)/16/P(8)/$/P(8)  E1   J1
292 Howard's Double C  jth 1885 *** BCM,J85 NJENO  Q2,M2,W3,Z2  x4
293 Howell's C  csh JENO 10x10:1$$1/1p(8)1/60/1P(8)1/1$1 >>157   H1
294 Hughes Four Handed C meh 1888 AJS IDC  M26,O15,Q1,W3,Z1    Y2
295 Hunter C  ks  NJEI  8x8:HuNFaQKFaNHu              G2
296 Hydra C  P=+K                          X3
297 Hyperchess wgg 69  Hypergames Company              k1
298 Hyperspace C  jh  73  Graustark 296               m2
299 Icelandic C   JENO                        T1
300 Identific C vrp  NA156  CCP                   B3
301 Imitator C avp  CS1                       R2
302 Immobilizer C  grd 86  %%%  10x10:RNIBQKBINR          V3
303 Incognito C  rb NA216,217                    X4
304 Incredulon  brt  86    %%%                  q5
305 Infinite Plane C  np, lr  52 NJENO               h4
306 Instant C  brt    %%%                    B1
307 Italian Billiards C   ES51                    J3
308 Italian Minichess  NA259,260,262  5x5:KQBNR  C-,E1       H2
309 Italian Progressive C  NA294,295  ES 1HO VC1-3 Pritchard   N3
310 Jabberwocky C  vrp  CCP New Scientist [Circum Morus]      j2
311 Jagged C  jag 70 J'A                      m1
  Japanese C == Shogi         
312 Jesskers  jdq  CL44:1p7                     g4
313 Jetan erb 22 ***  CVARM [Martian C]  10x10/20/8       c5
314 Jet C  72  r.NA168  Interplay, Inc.              p1
315 Johnson 3-D Chess  rj 67 NA115                 i1
316 Joyous C  ks 45  NJENO                     m3
317 Kaiser's Pre-Chess  kk 26 Funkschach,19S26 NJENO        B1
318 Kaissa jes 79  r.WGR3  Port Kar Industries          c5
319 Kaleidoscopic C   eml  NJENO                  W1
320 Kamikaze C  pm 65  AJS                     W1
321 Kidnapping C  hcg  NJENO                     B4
  King C == Letzen C       
  King Circe == Total Circe
322 Kinglet C  vrp NA182,220,248,257  NJENO  C-          X3
323 Kiwi Checkers jeb 90 NA319                   G4
   8/T1T1T1T1/1K1K1K1K/16/k1k1k1k1/1t1t1t1t/8
324 Klein Bottle C  C19                       j1
325 Kleptomaniac C  OCC [Pocket Knight C]               B2
326 Knight-Bishop Relay C  ro  NA183                Q1
327 Knightmate bz 72 J'A  8x8:RKBQNBKR               E
328 Knight Relay C  mc 72 NA166,183,189,190,209,217,222,231,232,  Q1
   257,262,268,304,305,308,317,319-321  ES30,38,40,50  NV'83
329 Knight Relay Giveaway ro 74  NA187,196             Q1
330 Knightrider Bouncy C  rab, stc 83  VC3   {6}         J3
331 Knight Supreme  wh  88 8x8:NNNQKNNN  ***  >>21        A1
332 Kogbetliantz (Kog) 3-D Chess  egk 52 *** NA89 NJENO  8x8x8  i1
  Korean C  == Changgi
333 Kriegspiel mht 1898  JENO NJENO G&P50 OCC NA202 C2,3 YM  s2
   J'A NCH IDC CVARM Anderson Bell
334 Kriegspiel Bughouse 76  >New Cincinnati Chess Club<       S2
335 Kristensen's C  ek 48 JENO  9x9                f1
336 Ladder-Board C rb NA253                     j1
337 Lazer C  sdf,rr  r.WGR7  Think Tank Games           u2
338 Lazy King C   NJENO                       B2
339 Lazy Susan C brt  %%%  R(cf36)cP               M1
340 Leaper Chessgi  grd 86  %%%                  g5
341 Leapfrog  bz 76 J'A                        G4
342 Legler's C  hl 26  NJENO  Chess Y52  8x8:RCBQKBNX      F1
343 Leo C  NA217  job  NJEI  P=QRBN               G3
344 Letzen C  el  NA191                       E
345 Lewis' C  jal 43  JENO                     A1
   4pnrk/4pbpr/4pbqn/4pppp/PPPP4/NQBP4/RPBP4/KRNP4
346 Liars C  rb 78  NA217  ES49,52,53               S1
347 Liberation C  dm, maj 71 J'A                  E
348 Lilac Tree C  NA106                       h3
349 Lilliputian C grd 86 %%%  6x6:RCQKCR  C2/1, P=QCRBN      H2
350 Lion C  grd 86 %%% 10x10:RNLBQKBDNR  L=Lion D=Duchess    G2
351 List C  rb  NA168  (also == Metamorphosis List C)        m1
352 The Little Game  JENO CVARM  NCH  3k4/ppp5/32/5PPP/4K3    A1
353 Lombard C  AHC                          c1
354 Longleaper C  grd 86  %%%  10x10:RNLBQKBLNR          g4
355 Looking-Glass C vrp  CCP                     O2
356 Los Alamos C  56  Kister 6x6:RNQKNR C-,E1,P=QRN        H2
  Losing C == Giveaway C     
357 Ludus Chessunculus  jrc 73 YFC8                 k1
358 Lumberjack C  bz 73 J'A                      L2
359 Luneburg C  tm 1821  CE   Q3,W2,Z2              y2
360 Machine Gun C  jec  GFC IDC AJS CS1 [Rapid Fire C]      U2
  Macrochess  == generic name for Ch1  CS2
361 Mad-Cap C  mc OCC VC5 JENO                  T1
362 Mad Mate  ar  G&P79 CR5                     v1
363 Madrasi C  ajk  C19 VC1 ESP1                 O2
364 Mad Threeparty C vrp NA156 CCP                 Y1
365 Magic C  fgm 23 ***                      D1
366 The Maharajah and the Sepoys   CVARM  NMDSA  JENO       A2
367 Maka-Dai-Dai Shogi   GSG  19x19/96               c3
368 Makrook  CS1,CVARM [Thai C] AHC [Siamese C]  C-,E1,P=(6)F    C4
   rnsfksnr/8/p(8)/16/...<>  K=K{N},F=F{E}
  Malay C == Chator                         c4
369 March Hare C  vrp NA156  CCP                  R1
370 Marseillais C  af NA35,296,299,301    ES OCC  JENO     N1
  Martian C == Jetan
371 Masonic C  grd 83  %%%                     k1
372 Maximummer C  trd 13  GFC  VC1,5                o1
373 Mecklenbeck C  be,bs NA284,299  FS 10/73   P=(678)      D2
374 Meddler's C vrp CDCD CDM ES53                 r1
375 Mediaeval C  AHC                         c1
376 Megachess  brt 75 NA194                    j1
377 Megarotation C  rb NA111  R(*3x3)eIU[R]            M1
378 Merger C  pmc 75   %%%                    m2
  Meta-Chess == Pre-Chess
379 Metamorphosis C  rb NA209                    s4
380 Metamorphosis List Chess  rb  NA209               s4
381 Mexican C pjk 65 10x10:RNMBQKBMNR  C3,E3,P=+M         G1
382 Microchess grd 87 %%% 7x7:RNBKBNR C22,E1,P=+Q B=B+noncap W  H2
383 Microchess-48 avp CS2 6x8:rnqknr/1b2b1/p(6)/12/... C-,E1,V1  H2
384 Microchess-49 avp CS2 7x7:RBNKBNR  C2,E1,P=RBN,V1       H2
385 Middle Ages C  NJENO VC5 1rekfer1/p6p/1pnppnp1/2p2p2/...    C1
  Middle Shogi  == Chu Shogi
386 Mimic C  ep                           R2
387 Minefield C                            M3
  Minichess == generic name for Ch2
388 Mirror Circe  C15                        v2
389 Mirror Rotofile C jag,dm 70 J'A                 m1
390 Missile C rws %%%   84        >>229           U2
391 Mock Butter C  vrp NA182  CCP                  U4
392 Mock C  vrp NA182  CDCD                     X1
393 Modern American C  84 10x10  Modern American Chess       d2
394 Modern C gvm 69 NA233 G&P23,25 9x9:RNBCKQBNR <> C2 Gabrielez F1
395 Modern Kriegspiel brt 86   %%%                S2
396 Moebius C  wp  53 C2,10,11,12                 j1
397 Monster C  4k3/p(8)/32/P(8)/$                  A2
398 Morley's C fvm  *** IDC JENO  10x8:-$$-/1p(8)1/40/1P(8)1/-$- H3
   (also 10x10:--6--/" "/--6--)
  Mosaic C == generic name for Ck
399 Moss C mm 71 NA263 YFC7 Montreal Star 16J71 J'A [Odious C]  T1
400 Mouterde's C  anm  JENO  10x8:-$$-/-p(8)-/40/-P(8)-/-$-    H3
   (also 12x8:--$$--/--p(8)--/-10-/24/-10-/--P(8)--/--$--)
401 Ms. Alice C  ji 73 NA165                    I2
402 Multimove Battle C  JENO                     B1
403 Multimove Dice C  CVARM                     N2
404 Multiplayer Melee C  rb 81  NA258                y3
405 Must-Capture C <1283  GFC VC5 NJENO AJS CS1 [Compulsion C]  T1
406 Mutation C  jeb  87 1HO  GPJ8  ES42,52,53  {7}       W1
407 Nayler-Ower C  jln,eo 28 BCM,C28 NJENO  10x8:RNBKQQKBNR    y2
  Nearest-Man Mover C == Proximity C
408 Neo-chaturanga  vrp  NJENO                    y2
   10x10:KQRBN3pk/P(5)3pq/8pr/8pb/8pn/np8/bp8/rp8/qp3P(5)/kp3NBRQK
409 Neochess ar 72  3M Corporation                 V1
  Neoschaak == Placement C
410 Neutral Conversion C  rb  NA169,231               R2
411 Neutral King C  vrp  NJENO  E1,P=RBN              R2
   rbnp4/rbnp4/pppp4/7K/8/PPPP4/RBNP4/RBNP4
  New England Double Bughouse C  == Double Bughouse C
412 Nightrider C  vrp NA148 NJEI r1bnkb1r/8/p(8)/16/...      G2
   N=Nightrider  E1,P=Nr  (pmc 8x8:RNrBQKBNrR, P=QRBNr)
413 Nilakantha's C   AHC                       c1
414 Nine File C  dw, dm 66 J'A  9x8:RNBQKSqBNR          G1
415 Ninerider C  pmc,rws 74  NA234  <>               G2
416 No-Capture C   NJENO                       T1
417 No-Castling C  eml  NJENO  C-                  O2
418 No-Entry C  dp 89                        O1
419 Nommenspiel  NA232                        S2
420 No-Retreat C  vrp,job  NJENO, NJEI               O2
421 NOST Spherical C  ln 72 NA185,186,188,192,196,219,222,224,227, J1
   253,259,301,302
422 Novak's Dice C  pn                        O3
  N-Relay == Knight-Relay C
423 Nuclear C  gac, brt 67 NA173,191                p2
424 Nuisance C pmc 79 NA232                     W1
425 Null C  pmc  64  NA174  YFC7                  W2
426 Oblique Cylinder C  YFC2                     j1
427 Oblong C  JENO  AHC  CVARM  4x16               c1
428 Octostar C  avp  CS2                      k3
  Odious C  == Moss C                
  One Check Wins == Single Check C
429 One-Shot C rb NA248                       O1
430 One-Two  NA33  $$/p(8)/32/2PPPP2/4K3              A2
  O/R Chess  == Overloader/Restorer C
431 Orbital C  rb NA168  R(ah18)a,(bg27)c,(cf36)a,(de45)c P=Q   M1
432 Orbital C bws, epd 69  SDM, Inc.                j2
433 Orion C sw WGR3  CV for Parker Brothers' Orion system     k3
434 Overloader/Restorer (O/R) Chess rb 74 NA177,195,225,229,248,  W1
   272,300  ES50
435 Padshah AHC CVARM [Turkish GC III] 12x12:RNBRBKQBRBNR <> E1,P=Q C2
436 Parallel Progressive C   GPJ1 ES30               N3
437 Parallel Time-Stream C  cmt 88 GPJ3              s1
438 Parsi C   AHC                          c4
439 Parton C  pmc 74 NA171                     p2
440 Partonic C  vrp NJEI  p(8)/$$/32/$/P(8)  ==>[533]       U3
441 Parton's Array vrp Chess Y52  NJENO  8x8:NBRRKQBN, C-     A1
442 Patrol C  C20                          T1
443 Patt-Schach VC5                          a1
   NRBKQBRN/1P(6)1/1P4P1/16/1p4p1/1p(6)1/nrbkqbrn  P==
444 Patzer C  CS1                           X5
445 Pawn Placement C  22  NJENO                   B1
446 Pawn Shop  $$/P(8)/16/P(32)                   A2
447 Pawn-Snatcher's Delight NA263  $$/16/p(8)/P(8)/16/$  E1     A1
448 P-Chess  jm  87  CL42:5(Y87)p51                D1
449 The Peasants' Revolt rlf 47 NCH JENO CL44:9(S89)p43ff CVARM IDC A2
   1nn1knn1/4p3/32/P(8)/4K3
450 Permanent Rotating Center C  whr,aef C2  R(de45)cP       M1
451 Permutation C  avp  CS1                     B1
452 Permuting C  jb, rl  NJEI                    E
453 Petroff's C  aop 1850  NA299  CE  JENO            y2
454 Petty C bww 30 BCM,S30 G&P66 NJENO OCC  5x6:QKBNR C2    H2
455 Phantom C  ra 78   Creative Computing             S2
456 Phantom C   CA,A10  NJENO                   B1
457 Phillips Chessers  60  Phillips                 O2
   4rbqk/5rbq/6rb/7r/R7/BR6/QBR5/KQBR4  V3
  Pigliatutto Progressivo == Progressive Take-All
458 Pinochle C  dm 70 J'A                      o3
459 Pinsard C  19  ESD  JENO                   g1
460 Pinwheel C  rb  NA166,168 R(ab12)a,(cd12)c,...(gh78)a  >>6   M1
461 Pivot C jag,dm 70  J'A                     m1
462 Placement C  evd 41  C-,E1  NJENO               B2
463 Plague C  rb 77  NA213                      u6
464 Plaid (Scottish Grid) C  whr NA168,191              L1
465 Plex   r.G98 (U89)  The Wickett Works              y3
466 Ploy  ft  Freeman G&P22  3M (later AH)             g5
467 Pocket Billiards C  jbv                      J3
468 Pocket Knight C  BCM,L84  OCC CR5 NJENO  CVARM        B2
469 Polyactive Transchess pmc NA233                 V2
470 Pre-Chess NA239,240,249,263,284 SC1 [Meta-Chess] NJENO J'A    B1
   CL(N78)pp609-613 NV'80  B3
471 Presto C  lsc 65  YM MCi                   X5
472 Progression C  avp  CS1                     D2
  Progressive Billiards  == Italian Billiards
  Progressive C == English P, Italian P, Scottish
473 Progressive Circe C rrg 79 NA262 ES34,35,38,39,41,44,45,47,48   V2
   1HO VC1 GPJ8,10 {8}
474 Progressive Giveaway  ES44-46                  X2
475 Progressive Kamikaze  ES51                    W1
476 Progressive Take-All gd 79 NA301,314,316            X1
   ES31,35,38,42,44,46,47  1HO  {9}
  Prohibition C == Checkless C
  Proteus C == Frankfurt C
477 Protochess  grd 86  %%%  8x8:DNEFWEND             c1
478 Proximity C  whr  AJS  IDC [Nearest-Man Mover]         O1
479 The Prussian National Game  bvh 1806  YFC8  CE  >>251    u2
480 Psychedelichess  brt                       q5
481 Push C  fg  NA232,242  C10                   U5
482 Putback C  NA164,170                       V2
483 Putback Transchess rb 74  NA170                 V2
484 Pyramid C  jdv  JENO                       M3
485 Qatranj  AHC CVARM [Turkish Great Chess II]            C2
   10x10:rnbckaqbnr/ppppvvpppp/4nn4/... <> E1
486 QuadraChess hs 77 NA216 N2/4/4a,W4  California Game Company  y2
487 Quadrant C  avp  CS1                       L2
488 Quadrivalent C  cb 45 OCC NA89  JENO  IDC [Total C] 4x8x8  i1
489 Quantum C  dae 68 Pentagon 27:99-103(Sp68) 6x8        g5
490 Quatre Quest-Chess  db 77  CR2                 y2
491 Quatrochess grd 86  %%%  15x15  N4/4a            y2
492 Queenless C   JENO 8x8:RNBCKBNR P=QRBN             F1
493 Queen Shogi                            C3
494 Quest-Chess db 74 NA183[Conquest C],214,262,286 CR Donald Benge n1
495 Racetrack C  dm 70 J'A                      j2
496 Racing Kings vrp NA95,179,191,215,228,233,250 ES49,53 NJEI   X6
   48/krbnNBRK/qrbnNBRQ
497 Rajah AHC CVARM [Turkish Great Chess IV]             C2
   14x14:RNBRBQQKVBRBNR <> E1,P=Q
498 Rampage  brt  NA194,211,214,226                 Q2
499 Randomized C  NJENO OCC  NA240   B123,C-           B1
500 Randomized Progressive  mah  B123                B1
501 Raumschach  fm 07  NA89 JENO C2 Dawson  5x5x5       I1
502 Reaction C  cmt  C11                      w1
503 Real C  eic  34  NJENO                     B1
504 Recaptureless Absorption C                     W1
505 Recaptureless C  avp  CS1                    T1
  Recon2 == Double Reversion Conversion C
506 Reflection C                            J3
507 Reflex C  bgl,wig 1885 CA,Y07 NJENO OCC C13 CS1       X5
508 Reform C  lt C12                         T2
509 Refusal C  fg  NA96 NJEI VC1,2                 O1
510 Reincarnation C  pmc 66 NA112,174,176-177,257,261,288 YFC7   W2
511 Reincarnation Circe C  ag C19                  V4
512 Relay C  mc 57 NA199  FCR9:15p121(A57)  IDC          Q1
  Replacement (Replacing) C == Bughouse C
513 Restricted Rotation C  pmc NA111  R(*2x2)eIUR         M1
514 Restriction C  fjm  NJENO                    O1
515 Retraction C  phj C15                      s1
516 Rettah C vrp 52 CDM NJENO NJEI NA182,183  >>2,183,208    E
   NJENO: rnkqqknr/2b2b2/p(8)/16/P(8)/2B2B2/RNKQQKNR C-,E1,P=+K
   CDM: 3nrbqk/3nrbpp/2p(6)/16/P(6)2/PPBRN3/KQBRN3 C-,E1,P=QRBN
517 Returner Board C  rb NA253                    J3
518 Reversed King and Queen  1881 JENO CL41:2(F86)p52 <>      A1
519 Reversed Minor Pieces  BCM,S03 NCH NJENO CVARM 8x8:RBNQKNBR  A1
520 Reversion Conversion C  rb 73 NA161,232             U1
521 Rhombic C  avp  CS2  72 diamond shaped cells          k3
522 Ricochet C  pmc 68  %%%                    j3
523 Rifle C  wbs 21  JENO NA204 OCC  VC2,3            U2
524 Right Angle C  dm 71  J'A                   j1
525 Riviere's C   adr  JENO 8x8:XNBQKBNX              F1
526 Robado C  V2                           X1
  Rotation C == generic for most of Cm1; also == Gumption C
527 Rotofile C  jag 70 J'A                     m1
  Round C  == Byzantine C; Circular C
528 Royal Fury  vrp  CDM, MGTA                    u7
529 Royal Pretender C  jjs C8                    X3
530 Royal Scaci Partonici  vrp NA156  CCP IPG           U3
531 Rutland's C dor 1747  ChCh CE  14x10:RTNBBXKQBBNNTR E3   C2
532 San-Kwo-Chi   CVARM AHC  Wurman                c4
  Sans Prise  == No-Capture C
533 Scaci Partonici  vrp  CCP IPG NA156              U3
534 Sceptre 1027 A.D.  86  r.WGR7  Horizon Games          y3
535 Schach Plus  ros                         m2
536 Schess dm 73 J'A                        h1
537 Scottish [Progressive] C  NA33,94,95,101,144,161,163-165,169,175, N3
   178,181-183,189,220,224,244,263,264,268
   ES46,49,50 VC1-3,5 JENO OCC  NV'82
538 Scottish Chessgi  NA177                     V1
539 Scottish Co-Regal  NA181                     X4
  Scottish Grid == Plaid C
540 Scottish Kinglet C     NV'84                  X3
541 Scottish Knight Relay NA178,181                  Q1
542 Scottish Modern C brt NA151,153,167,175,178,250,262,290 ES49,53 N3
543 Scottish Rifle C  NJEI                      U2
544 Screen C avp  CS1   (also == Battle C; Kriegspiel)       G3
545 Self's 3-Handed C  hjs 1896 ***                y1
546 Semi-Queen C  vrp  NA182 CDM  CDCD,HSCD,ESD [Half-Queen's C]  F2
   10x10:RNBOQKIBNR (CDCD/HSCD), riobqkboir/ppppnnpppp/40/... (CDM)
   C-,E3n,P=+OI
547 Shatranj AHC NA167,171,303 CS1 [Medieval C] OCC CVARM VC5  C1
   JENO  8x8:RNEFKENR C-,E1,P=F,V12
548 Shatranj al-Husun  AHC  CVARM 10x10:RNEBKFBENR C-,E1,P=F,V12  c2
549 Shatranj al-Kabir  AHC CE CVARM    E1  g=Giraffe      C2
   13x13:rnbcmqkgmcbnr/26/p(13)/...
  Shatranj Diwana Shah == Maharajah and the Sepoys
550 Shatranj Kamil AHC CVARM  CE  C-,E1,P==F,V13         c2
   10x10:rnevfkvenr/10/p(10)/40/...
551 Shazzan! brt    %%%                      W2
552 Shogi (Japanese C) NA113,145,201,230,234,236,240,243,247,300,307, c3
   308,312,325 G&P24,28 ES29,31,51-53 OCC CL40:12(D85)p40 IDC
   VC2 JENO G90(M88) SA SH SW Arnold Fairbairn Leggett
   Ohara Pritchard Teruichi(1,2) 9x9/20/8,3,10   p.12
553 Shoot C   wbs  BCM,F90  VC2   {10}              U2
554 Short Assize C   AHC                       c1
555 Shrinking Board C  job 54 NJENO NJEI              M2
556 Simoco dm 73 J'A                        h1
557 Simpleton's Duffery  vrp  CDM                  X6
558 Simplified C  clf 31  6x8:RBQKBR  NJENO            H2
559 Single Check C fh BCM,U16(36:426) MCi NJENO $$/8/p(8)/16/...  X5
560 Six-Dimensional C  cgl  78 YFC8                 i3
561 Six-Handed C  mxl 1881 CE  JENO  24x8:$$,$$,$$/P(24)/96/...  y3
562 Sixteen Pawns ldk  NA162 JENO OCC [Pawns Game]         A2
563 Skid Row C  pmc 78 NA217                    l1
564 Slater's Four-handed C  es  NJENO 8x8:KQBNNBQK         y2
565 Slippery Center C  pmc 70 NA215                 L1
566 Slow Scotch  brt                         N3
567 Smess  pg  G&P3-5 [Take The Brain]  Freeman  Parker Brothers  l2
568 Sniper C avp CS1                         F2
569 Snowplow C  dls  YM                       T2
570 Soldier C  avp  CS1                       D1
571 Space Chess 69 3x8x8  Pacific Game Company           i1
   (also == Raumschach, and generic term for 3-D chess)
572 Space Shogi  grd 87  %%%  3x3x9                i1
573 Sphericalice C  ln  NA188                    I2
574 Spherical C  dlm 65 YFC2  GFC  NA185   NJEI (hdg)      j1
575 Spherical Shogi  grd 88  %%%  10x9              j1
576 Sphinx C  vrp NA156 CCCS                    I3
   3x3x4x4:1rn1 bqkb 1nr1/p2p 4 p2p/24/4 pppp 4/24/...
577 Spite C  dls 73  NA178,181,184                 U6
578 Spite Chess plus Chess  rb  NA181                U6
579 Splice C  dm 70 J'A                       s2
580 Sputnik C  jb,rl  NJEI                      N2
581 Spy C  16  AJS                         S2
582 Stacking C    AJS                        P1
583 Stationary King C                         X5
584 Stereo-Chess  gwj 75  ESP2  8x8 plus 4x4x4          I1
585 Straights Rotofile C dm 70  J'A                 m1
586 Strange-Relay C  rb 80  NA263  ES50              Q1
587 Suction C  rb 79 NA238                     V2
588 The Sultan's Game  llt 1840 CE  11x11:RBNXAKQCBNR C4     F1
589 Supercapablanca C sac 73 NA178 12x8:RNBCXQKACBNR C234a,P=+AXC F1
590 Super C eg 86 NA324 r.WGR7 Super Chess, Inc. p.11(News)   u7
591 Superpawn C  nv  NJEI                      D1
592 Super Pre-chess  hwk  77  NA240  B3              b1
593 Surge C  pmc 73  NA167,183                   Q3
  Survival of the Species  (original name) == Extinction C
594 Swarm C  rb NA248                        N1
595 Symmetric Circe  C15                       V2
596 Symmetric Pre-Chess eb 28 JENO,NJENO OCC [Randomized C] B2,C2 B1
597 Synchronistic C  vrp NA156 CCP                 S3
  Tag C  == Moss C; Spite C; one form of Reaction C
598 Tai Shogi  GSG NA230,236   25x25/177             c3
599 Takeback Kriegspiel  ep  NA312                  S2
600 Take Me  wc 1876 OCC  CE  P==                X2
  Take The Brain  == Smess (U.K. edition)
601 Tamerlane Cubic C vrp CCCS NA156   Z=Zurafa          i1
   6x6x6:144//denned/p(6)/12/P(6)/DENNED//rzkfzr/p(6)/12/P(6)/RZFKZR
602 Tamerlane's C AHC ES52,53 CVARM [Timur's C] JENO NA308     c2
603 Tandem C  avp CS1                        v1
604 Tank C  kjg  CS1  GFC                     u5
605 Taxi (Pawn) C  kf 61 CS1  GFC                 D1
606 Tedco 3-D Chess NA90-91 4x4x4 Texas Educational Devices Co.   i1
607 Telegraph C  NA223  ==> U-Chess                 o1
608 Teleportation C  rws 84    %%%                Q2
609 Teleport C avp  CS1                       Q2
610 Tenjiku Shogi   SA  16x16/78                  c3
611 Tesche's 3-Handed C  wt 1843  CE                y1
  Thai C  == Makrook
612 Thinktank C  fgm  27  VC2                   f2
613 Third World C  81        D. F. Thomson Co.        y1
614 Three-Dimensional C  79 4x4x4 Enjoyable Hour Products      i1
   (also == generic name for Ci1  CVARM)
615 Three Man C grd 84  %%%                    y1
616 Three-Player C  rz  71  Carter Hall              y1
617 Threespace C avp  CS1                      O2
618 Threesum C  avp CS1                       N2
619 Time Warp Rotofile C  dm 70 J'A                 m1
  Timur's C == Tamerlane's C
620 Token C dp 89                          V1
  Tombola == Pocket Knight C
621 Tori Shogi tg 1828  SA NA296,297 G95(J89)  7x7/16/7,2,9   c3
622 Toroidal C C2,3,7                         J1
   (cmt):4nppr/4pqbp/4pkbp/4nppr/NPPN4/PQKP4/PBBP4/RPPR4
623 Toroidal Pre-Chess pmc 80 NA248                 B1
  Total C == Quadrivalent C
624 Total Circe C   C8,18                      V2
625 Total Kamikaze C  C12                       W1
626 Trabue's C  iht 04  ***   Q1,W3               y2
627 Transcendental C ml 78 Zugzwang M79 TC NA253 B13,C- TC/Lawrence b1
628 Transportation C (Transchess) rb 73 NA169-171,179,181,196,216,225,229,262,313,319  ES50,52    V2  
  Triagonal C  J'A CS2  == name for proposed game        k2
629 Triangular C  grd 86  %%%                   k2
630 Triboard C   grd 85  %%%                   k3
631 Tri-Chess ap 75 OCC G&P79  Tri-Chess, Inc.          k1
632 Tri-Chess  a.CL40:2(F85)p45  Trigame Enterprises, Inc.     y1
633 Trichess grd 86  %%%                      k2
  Tricolor C == De Vasa's C  (also == generic for Ck1)
634 Triple C  fim 1722  *** JENO   Q1,P=|,3W3,Z1        y1
635 Triplets  as  NA322,324 ES53  NV'90 {11}           N1
636 Triscacia  vrp  CDM                      Y1
637 Trishogi  grd 87  %%%                     k2
638 Turkish Decimal C  CS2 CVARM [Turkish Great Chess I]       c2
   10x10:rnbqkacbnr/ppppxxpppp/4pp4/... <> E1,P=Q
  Turkish Great C  CVARM (== 638,485,435,497)
  Turnabout C  == Gumption C
639 Turncoat C   C7                         V1
640 Turning Cube C eb 24  NJENO                   b5
641 Twinkle C  rb 77 NA214,218  ES53                B4
  Twin Orthodox C == Chess Tweedle
642 2000 A.D. vrp  72   MGTA  NA230,247              u7
643 U-Chess (Unambiguous Three-Symbol C) mc,ic 53 NA55,142,178-180,190,202,217,222,223,259 FCR 8:12p88(C53) C2 ES49 IDC    O1
644 U-Giveaway  NA178,191                       O1
645 U-Grid   NA184                          L1
646 Ultima ra 61 *** NA103-105,107,110-111,158,170,183,216,220,221,224,227,233,251,252,266,276-278,292,307 WGR5-8 ES48,50 RMM (10:29-34; G62) [Baroque]    u7
647 Ulti-Matem  brt  NA91                      U7
648 Ultrachess  hab  Word Ways,2:4p235  12x12            p2
649 Unfamiliar Ultima  rb, pmc  73                  u7
650 Union C  fgm 25  NJENO                     P2
651 Unirexal C  vrp   CCP                      X6
652 Universion C  rb  NA232                     R1
653 Unorthodox Ultima  jst  NA86                   u7
654 Upside-Down C gpj VC5  RNBKQBNR/P(8)/32/p(8)/rnbkqbnr      A1
655 U-Scottish C  ro  NA169,178                   O1
656 Valentine's C kv  IFW Monthly 2:1(J69)  10x10/30/14       f1
657 Vault C  avp  CS1                        G3
658 Vegas Fun C     Vegas Fun Chess                o3
659 Vendetta     W4  commercial -- publisher unknown       y2
660 Verney Four-Handed C ghv 1881 AJS NCH C-,E1,M26*4,O15,Q4,W3,Z1 Y2
  Vertical Cylinder C == Cylindrical C
661 Very Scotch C rb NA205                      N3
662 Very Slippery Center C  pmc 77 NA215              L1
663 Viennese Kriegspiel 08 NJENO                   B1
  Vinciperdi == Giveaway C
664 Wagon Wheel C    GFC                      J2
665 Waider's 3-Handed C  ssw 1837  JENO, CE            y1
666 Wardley's C aw 77 G&P66                     h2
667 Warrior C avp CS2  7x7:RNQKSpNR  Sp>Warrior          G2
668 Wa Shogi  SA  11x11/27/17,13,25                 c3
669 Weak! rb  NA162  nnnnknnn/p(8)/2p2p2/1p(6)1/16/P(8)/$ BP=N   A2
670 Wellisch 3-Handed C  siw 12  OCC                k1
671 Wildebeest C rws 87  %%%  NA303-305,311,312          G1
   11x10:RNMMWKQBBNR  C1234,E5,P=QW,V1     W=Wildebeest (Gnu; N+M)
672 Withdrawer C  grd 86  %%%  10x10:RNWBQKBWNR          u6
673 Wizard C  avp  CS1                        Q1
674 Wolf C  avw  NJEI   VC6 (to appear)              f1
675 Wyvern C vrp CDCD HSCD  10x10:RNABQKBANR  A>Wyvern      F1
676 Xiang Qi (Chinese C)  NA160,181,190  G&P19,27,49,52,63 VC1,3,5 c4 ES49-53 CVARM OCC JENO AHC Arnold Donnelly Lai Lau Pritchard Sloan Wurman  p.12-15
677 Zombie C  pmc NA112,174,175  YFC7                W2

Copyright ©2020 by Michael Keller. All rights reserved. This booklet was published on May 24, 2020.