Absolute Checkless Chess Checks and passing checks, except checkmate, are banned. [R.Powell Chessics 1976]

ACTUATED CENTRE CHESS The group of four central cells (de45) rotates when actuated; the methods of actuation can be: by moves across (A), exterior to (E), into (I) out of (O), or upon (U) the centre, or any combination thereof; the rotation can be 90° anticlockwise (+) or clockwise (–) or 180° whichever is specified.
      The original type [W. H. Rawlings and A. E. Farebrother Fairy Chess Review 1937] was ARC-IU(–) chess, though some sources describe it as IO or IOU type. Many of these cases have not yet been tried; perhaps ARC-I(–)/O(+) would be more balanced (i.e. rotate clockwise on entry, anticlockwise on exit). èRotating centre chess = ARC-AEIOU chess

ajedrez (Spanish) = chess.

Akenhead's Game Chess in which queen, rook, bishop and knight are replaced by leo, pao, vao and mao, and berolina pawns are used. [J. Akenhead Fairy Chess Review April 1947].

Aleut Chess A form of chess played in Alaska about which little is known. See Yakutat Chess.

Alice Chess Variant using a second board, initially empty; after a move on one board the moved piece is transferred to the corresponding cell on the other board; this cell must be vacant, or the move cannot go ahead; kings may not move through check. [V.R.Parton Fairy Chess Review 1954]. Article in VC: Alice Chess

All-in Chess Each player may, on his turn, move one of the opponent's men instead of his own; however, a player may not reverse the move just made by the opponent. [C. M. B. Tylor Chessics #1 March 1976]

"Anchor Ring Chess" = Toral chess.

Andernach Chess A unit other than K changes colour on making a capture.

Anti-Chess Any variant in which kings are replaced by anti-kings (which are in check only when NOT attacked). It requires an initial position with Ks under attack, e.g. the usual array on a horizontal cylinder.

Anti-Circe Chess A capture is only permitted if the home cell of the capturing unit is vacant. After capturing, the capturing unit jumps to its home cell.

Antipodean Chess A captured piece reappears at the antipode of the capture cell, that is the cell a {4,4} leap away, provided that cell is vacant on arrival. Can be rex inclusive or exclusive. Other subvariants arise depending on the rules adopted for treating pawns sent to the 1st or 8th ranks. [G.P.Jelliss Chessics 1976].

"Arabian Chess" = Shatranj.

Arrow Chess Any piece that checks also guards the two cells in the king's field to left and right of the check line. The check line and the two prevented flights thus form an arrowhead. [G.P.Jelliss Rex Multiplex 1985]. èAKM: arrow pieces

Ashtapada [Sanskrit] The 8 by 8 board or any game on it.

ASTRONOMICAL CHESS Any form of chess played on a board symbolising the celestial sphere and with pieces representing heavenly bodies. Such games are mentioned in mediaeval manuscripts. However, that in the Alfonso X collection, although called "Los Escaques" is not a chess at all, but more a type of backgammon.

Augsburg Chess Pieces of the same side can combine and separate. VC article on problems by Ronald Turnbull VC25 1997. Also includes Iceberg Chess.

Avalanche Chess After each move a player must move an opposing pawn one cell forward (unless no pawn can so move). A pawn pulled to the end rank promotes to value chosen by its owner. Capture move by pawn may be allowed or barred.

BAROQUE CHESS Any variant in which the method or methods of capture are unorthodox. The pawn's en passant capture is the only baroque capture in orthodox chess. èAKM: locust

Berolina Chess Game (invented in Berlin) in which the berolina pawns travel one step diagonally forward (or two steps from the initial pawn rank, subject to e.p. capture) and capture by one step directly forward.

Berolina Plus Chess Berolina chess in which the pawns can also capture by single steps sideways along the rank on which they stand.

BIFID CHESS Any variant in which white plays according to one set of rules and black another; e.g. U-chess versus Grid chess. [R.Betza NOSTalgia nr.209].

Bird's Game Same as Carrera's game but with R+N (‘guard’) on d-file and B+N (‘equerry’) on g-file. [H.E.Bird, The City of London Chess Magazine 1874].

Blindfold Chess In which one or both players do not see the board but are told the moves. The first known blindfold player was an African player of Shatranj, Sa'id bin Jubair (ad 665-714).

Brunner Chess Releasing one's king from check takes precedence over capture of the opposing king.

E.Brunner Fairy Chess Review 1939
Mate in 2 Solution: 1.Q×f6† K×f6† 2.R×g6‡ This 'impossible' mate with 2Rs and N is famous as shown by Sam Loyd in an engraving in American Chess Journal 1876 which has the chessmaster Harwitz pondering a board with this absurd position upon it. There is another example of this type of mate in èTwo-move chess.

Bughouse Chess A game for teams of two who play simultaneously, each side having white on one board and black on the other; a player who captures a man passes it to his partner, who may drop it as in Chessgi; the game is usually played at blitz speed, and the first mate or flag-fall determines the result. [Details from P. Byway, VC vol 5 issue 00, Autumn 1999]

Bug-eyed Monster Chess Each piece makes any move which is not that of the orthodox piece. [M.Crumlish].

Bystander Chess A joke variant, in which the board is rotated through a right angle so that the players look at the position side-on, with the idea of giving them a less confrontational perspective on the game. [F.Maus Chess Amateur September 1927 p.378].

Capablanca's Game The name of the former world chess champion has become associated with several variants, but especially a 10 by 10 version of èCarrera's game, with R+N on h-file and B+N on c-file, and pawns allowed a one-, two- or three-step initial move. [D. Pritchard cites American Chess Bulletin November 1925] èDasapada.

Carrera's Game Chess on a board 10 files wide (8 ranks), with knighted rook (centauro) on b-file and knighted bishop (campione) on i-file [Pietro Carrera, Il Gioco degli Scacchi {The Game of Chess} 1617].

Chancellor Chess An expanded chess on 9 by 9 board, with knighted rook ("chancellor") f1 and Ng1, Bh1 to ensure bishops run on opposite colour squares [B.R.Foster St Louis Globe Democrat 12/ii/1887].

Changgi = Korean chess. Similar to Chinese chess (Xiangqi). The main differences are: (1) the cannon moves in the same way that it captures (i.e. it is a "rook-lion"); (2) the elephant moves one step forward and two steps diagonally forward, through vacant cells (like a blockable "zebra"); (3) In the opening position the General stands in the centre of the nine-castle. The General and his Guards move as wazirs, and along the main diagonals of the nine-castle. (4) Chariot, Cannon and Soldier can also move along the diagonal lines when within a palace. (5) Cannon may not leap cannon. [Murray (1913) pp.134-7, based his account on that of W.H.Wilkinson in S.Culin's Korean Games 1895.]

Chatrang The Middle Persian form of chess. The Chatrang-namak, tells of the introduction of chess to Persia from India in the time of Khusraw I (Shah ad 531-578). The names of the pieces are given: Shah (king), Rukh (chariot), Farzin (counsellor), Pil (elephant), Asp (horse), Piyada (foot-soldier), but not their moves. It is made clear that it is a two-handed game of skill. The term ‘mate’ comes from the Persian mat (lost).

Chaturaji A four-handed version of chaturanga, played with dice; opening position as shown the pieces being king (raja = ruler), rook (gaja = elephant), knight (aswa or turanga = horse), alfil (nauka = boat) and pawns (vati = foot-soldiers) having no double step.

The game was played for stakes with two 4-sided dice; throws indicating which type of piece is to be moved; 1 = P or K, 2 = A, 3 = N, 4 = R. [Described in al-Beruni India c.1030ad and Raghunandana Tithitattva c.1500ad; H.J.R.Murray A History of Chess 1913 pp.58, 68-77.].

Chaturanga The early Indian form of chess. The word is supposed to refer to the "four branches" of the army: chariots, elephants, cavalry and infantry. The earliest extant account of the Indian game, apart from vague allusions, is from al-Adli (c.840) quoted in the al-Baghdadi manuscript (1140).

Checkless Chess No player may check except to checkmate. A score of a game between Sickel and Max Lange played in 1856 was reported in Sammlung neuer Schachpartien Leipzig 1857 (quoted in Cahiers de l'Echiquier Francais vol.2 1929-32 p.405):
è1.e4 e5 2.Nc3 Nf6 3.Bc4 b5 4.B×b5 c6 5.Bc4 d5 6.e×d5 c×d5 7.Bb3 Ba6 8.f3 Qb6 9.d3 Bb4 10.Ke2 d4 11.Kf2 (stops P×N) Nc6 12.Na4 Kd7 (stops N×Q) 13.B×f7 Raf8 14.Bb3 g5 15.c3 Bd6 16.c×d4 g4 17.f×g4 Re8 (else 18.g5 and 19.g×f6) 18.Ke3 Rhf8 19.Ne2 Ne4 (20.d×e4? Bb4) 20.Nec3 Nf2 21.Rf1 N×d3 22.Rf5 Bb4 23.Ne4 h5 24.a3 Ba5 25.Nd6 h×g4 26.N×e8 N×c1 (threat Q×d4‡ since Q×Q† prohibited) 27.Nd6 N×b3 28.Q×b3 R×f5 (missing Q×d4‡) 29.N×f5 Qd8 30.d5 Qf8 31.Ke4 Bb6 32.Rc1 Ne7 (threat Q×f5‡) 33.Q×b6 a×b6 34.K×e5 N×f5 35.Re1 Ke7 36.Re4 Bd3 37.R×g4 Qb8‡ (d6† prohibited).
      [Invented c.1830 according to Anthony Dickins (‘Fairy Chess’ article in A.Sunnucks Encyclopaedia of Chess 1976) but he does not cite a source.]
      A difficulty with the checkless rule is: what happens when Black can stop what appears to be a mate by a move that appears to mate White, and then White can stop this one by a move that appears to mate Black again, and so on? Sequences of two or three ‘counter-mates’ of this type have been shown. e.g.:

H.Stapff feenschach 1950
Checkless chess. Mate in 2 Solution: 1.Rf5 for 2.Bb3 mate
(2..Kb5 mate? not allowed since 3.Na3 mate!)
Try: 1.R×Q? R×R 2.Bb3
(not now mate since Kb5 is mate).
Try: 1.R else? Bg6 2.Bb3 mate? Kb5 mate?
3.Na3 mate? R×a3 mate!

To avoid this mind-boggling situation it seems that the rule should be adopted that ‘countermates’ are also prohibited: the first to checkmate wins.

CHESS A family of games abstractly simulating battle, believed to have originated in 5-6th century India or China, and the many similar games invented since, most of which are characterised by (a) the use of a variety of pieces with different powers, (b) the presence of a royal piece on each side whose capture or entrapment is the primary objective of play, (c) the presence of less powerful pieces (pawns) in front of the main pieces, not able to move backwards, and capable of becoming more powerful in the course of the game, (d) absence of chance factors, such as dice-throwing or hidden information as in card games.

Chess The international form of chess codified by the FIDE since the 1920s; in describing other forms of chess we take the FIDE laws as applying except where indicated otherwise.

Chessgi Chess in which a captured man changes colour and, later in the game, in place of a normal move, can be replaced anywhere on the board by the capturer, except that pawns cannot go to the end ranks; to play this game a second set is needed, or a special set of invertible pieces; the name is a meld of chess and shogi. See VC59 2009. èHostage chess.

Chess in Disguise All or some of the pieces are disguised as draughtsmen, whose identities are revealed when captured or must be deduced in the course of the game by their moves or checks. èknighted chess in disguise

Chinese Chess = Xiangqi.

Chinoise Chess Chess with Leo, Pao, Vao, Mao replacing Queen, Rook, Bishop and Knight. èAkenhead's game, Leo chess

CIRCE CHESS Any variant in which captured pieces are replaced on squares related to their initial position in the game array.
      The name "Circe" is misapplied by some editors to virtually any game in which normal capture is replaced by a variant form of capture involving reappearance of one or both participants elsewhere on the board. In such cases it is better to use a name that gives a clearer indication of the specific rule involved. For instance, I particularly object to my invention Antipodean Chess being termed "Antipodean Circe". Circe Chess In which a captured piece is immediately replaced on its home square if vacant; but if the home square is occupied the capture is normal. In problems, since the home square cannot usually be determined from the position given, a captured rook or knight is returned to the home square of the same colour as the capture square, and a captured pawn is returned to the pawn square in the file of capture. [P.Monreal and J.P.Boyer Problème 1968]. This game gives rise to many variants.

CIRCULAR CHESS Chess played on a board with 4 circular ranks and 16 radial files; the opening position can be regarded as formed by splitting the usual board between the K and Q files and joining the short ends of the two halves; the original game [described by al-Masudi 947] used the fers and alfil of mediaeval chess, with K and F of one colour interchanged so that the two fers move on the same set of cells, and there was no promotion; if two pawns met head-on the pair was removed. èCylinder chess
      A modern version, played at Lincoln, uses Q and B and has no en passant capture or castling [Variant Chess #31 1999]. Article in VC: Circular Chess

COMPUTER CHESS Any form of chess played against or with the help of an electronic computer.

"Corean Chess" = Korean Chess.

Coronation Chess “After a player has lost Q, he may move B to R or R to B and replace them with Q ... If this new Q is lost the player may then Coronate another Q provided remaining R and B are still on the board.” Promotion is to captured pieces only. [F.Maus Chess Amateur May 1925].

Courier Chess A 12 by 8 variant of mediaeval chess, played in Germany; White back row: Rook, Knight, Alfil, Kurrier (meaning Courier and moving as modern Bishop), Mann (meaning counsellor or sage and moving as non-royal king), King, Fers, Schleich (meaning spy or sneak and moving as Wazir), Courier, Alfil, Knight, Rook. [Described by Selenus 1616] VC article by Paul Byway: VC8 1992 èModern courier chess.

Cylinder Chess Chess in which the left and right sides of the board are supposed joined and pieces can cross this line; èCircular chess, Horizontal cylinder, Mobius chess, Torus. Article in VC: Cylinder Chess

DASAPADA [Sanskrit] A 10 by 10 board or any game on it. Used e.g. by V. R. Parton in his booklet Enduring Spirit of Dasapada. The usual proposal is to add two pieces (and their accompanying pawns) to each side. The earliest recorded example is that of al-Khalil b.Ahmad (c.ad750) who placed ‘camels’ of unknown powers at the ends of the baseline. The most popular pieces to add are knighted rook and knighted bishop. It is also advisable to increase the powers of pawn movement. èCapablanca's game, Grand chess

DECIMAL CHESS Any chess on a board of 10 files. èCapablanca's game, Carrera's game, Dasapada

Double-Move Chess See Two-Move Chess.

Dynamo Chess There are no normal captures, instead captures are by pushing or pulling pieces over the edges of the board. A piece can only push or pull one other piece at a time (two constitute a block). Pawns do not pull, and they act diagonally on enemies, orthogonally on allies.

ENLARGED CHESS Any chess on a board larger than 8 by 8. èExtended chess. Widened chess. The board can be simultaneously widened and deepened: èCapablanca's game, Dasapada, Timur's game, Twenty-first century chess

EXTENDED CHESS Any variant in which the board is deepened to 8 by 9 or 8 by 10 or longer. It is possible to increase the number of ranks without altering any other rule. Fool's mate in 8 by 9 chess is: 1.f4 d6 2.g4 Bh4‡. However to speed up contact of forces it may be necessary to give the pawns extra moves, typically one extra step initially for every two extra ranks, or to advance the pawn row. The powers of the officers may also be increased. èWolf chess; AKM: Opting pawn

Extinction Chess A player loses when his last piece of any species is captured. Thus any piece that is the last of its kind becomes royal; it cannot be exposed to or left in check.

FAIRY CHESS This term was first used by Henry Tate, chess columnist of The Australasian, 20 June 1914, who wrote, concerning unorthodox chess problems: “The old form of the eccentric, built upon illegality and trickery, has given place, curiously enough, to an extremely fanciful and delicate structure, which is usually based on the strictest logical principles.” The term was taken up and the subject developed energetically in Chess Amateur and later Fairy Chess Review by T. R. Dawson, who wrote, in Caissa's Wild Roses 1935: “Normal chess is evidently an arbitrary group of elements selected from an infinity of analogous geometrical conceptions. Fairy Chess comprises the study of all such elements, taken in arbitrary groups at will.” The current tendency is to restrict this term to apply to chess with unorthodox pieces and to use 'Variant', 'Heterodox', 'Unorthodox' or 'Generalised' chess for the wider subject.

Fischerrandom See Randomised chess.

Foster's Game. = Chancellor chess.

FOUR-HANDED CHESS Any variant for four players; the play can be free-for-all or two-against-two. If each player has the usual game array a large board at least 12 by 12 is needed to fit the forces in the middle of each side; and to avoid the rook pawns coming into direct contact a 14 by 14 board is necessary. It is natural to leave out the corner areas, resulting in a cross-shaped board. [G.H.Verney Chess Eccentricities 1885].
      Here is a partnership version with minimum variance from the orthodox: simply replace the queens by kings, and mark the queen-side pieces; thus each player has K, R, B, N and 4P; the move sequence being wk, bk, wq, bq. èCharuraji

FREE PLACEMENT CHESS The basic idea is that initially the board is empty, the players place their usual 16 men on the board one at a time alternately until they are all present, and then the play starts as usual; many variations on this scheme have been proposed. èFree programme chess

Free Programme Chess Each player places his pieces only on his own half of the board; kings are placed first; one bishop on each colour; pawns not on the first rank, and have the double move only from the second rank; white may not capture at the first move. [Gela Guraspasvili, Tbilisi, Georgia, 1995].
      In the games as played in the original experimental tournament in Tbilisi the kings were always placed on the back rank, and no piece was ever placed so as to give check, but these were not explicit rules. VC articles by George Jelliss VC26 and VC28 1997/98

GENERALISED CHESS A wider field than Variant Chess, including mathematical theory of moves, knight's tours, arrangement puzzles, grid dissections, step-by-step transformations and so on.

Grand Chess Dasapada with R+N ("Marshall")and B+N ("Cardinal") placed between K and B, and then all pieces and pawns, except the rooks moved forward one step (thus no castling); pawns may promote on reaching the 8th or 9th ranks but do not have to until they reach the 10th [Christiaan Freeling 1984]. VC article by Malcolm Horne VC24 1997 See also VC63 2010.

GREAT CHESS Any form of chess on an enlarged board with extra pieces; èGrand chess, Bird, Carrera, Timur

GRID CHESS The board is marked with lines between some of the cells and every move must cross at least one grid line. The original and most popular arrangement of the lines, which makes a playable game, is the standard grid which divides the board into 16 areas, each 2 by 2. [Walter Stead, Fairy Chess Review 1953] è Grid Chess Article with problems: Grid Chess. Another playable form is the slipped grid, like the standard grid but moved one file right; in this form the kings can reach the corner cells. Many other arrangements of grid lines have been tried.

Hamburg Space Chess A form of èSpace chess using a 5×5×5 board, developed by the Hamburg Space Chess club founded 1908 by Dr Ferdinand Maack with Hans Klüver and W.Roese among its members; T.R.Dawson advocated this variant and gave an extensive account of it in Chess Amateur 1926. The white Ps begin on rows A2 and B2 and promote on row E5, while the black pawns start on E4 and D4 and promote on A1; they move as wazir and capture as fers in the "forward" directions (i.e. towards promotion); and may thus have up to 2 travel moves and 5 captures available. The pieces begin with RNKNR on rows A1 and E5, and BUQUB on rows B1 and D5; where U is for unicorn, the (1,1,1)-rider; the two white unicorns run in the same sets of cells as the two black unicorns. To be avoided from this opening position is: 1.NAb1-Bb3 UDd5×N. A fool's mate is 1.Q-Ec1 B-Ca5 2.N-Cb2 P-Ea3 3.N-Eb3‡

HANDICAP CHESS Any variant designed to even up the balance between an experienced and less experienced player. The only really fair way is to allow the weaker player more time and perhaps access to reference or even computing aids. The time factor for example is what evens up the odds in a simultaneous display. In the nineteenth century the giving of odds was popular; that is the stronger player does without one or more pawns or pieces, or the weaker player is allowed two moves to start, for example.

HEXAGONAL CHESS Any game on a board of cells arranged in a honeycomb lattice, in which each cell has six adjacent cells around it; there are many different types.

Horizontal Cylinder Chess In horizontal cylinder chess the top and bottom edges of the board are considered to be joined. With the orthodox opening position this means that each king starts in quadruple check, so either some other opening position has to be devised or some rules to accommodate these checks. èAnti-chess, Cylinder chess, Toral chess.

Hostage Chess A captured man is placed in the capturer's Prison. On a later turn it may be exchanged for for a captured man of equal or lower value (P < N = B < R < Q). The recovered man must be immediately parachuted back into play; the released man is held in reserve and can be parachuted back into play on any subsequent turn. A pawn can promote only if there is a piece in prison for which it can be exchanged. Article in VC32 1999. [John Leslie 1999] The author's own website Hostage Chess offers a book and computer program. è Chessgi.

Iceberg Chess A variant of Augsburg Chess [Peter Fayers, VC25 1997]. See Augsburg Chess.

Imitator Chess A marker, neither white nor black, that imitates length and direction of every move, and prevents any move that it cannot imitate, is placed on a central cell at start of play.

Indian Chess Murray (1913) reported many variations in the rules of chess in the Indian subcontinent in both space and time. The following account of the differences between Indian and European chess at the beginning of the 19th century is summarised from that given by T. Shastri Essays on Chess 1814 (as reported to me by John Beasley). (1) K to right of Q in opening position for each player. (2) Bare king (boorj) may count as win or draw in diferent places. (3) Stalemate is not allowed; some play that stalemated player may remove an adverse piece. (4) Repetition not allowed. (5) Pawn promotes to the master piece of the file (Q in K file). Promoted knight on unguarded promotion square has a free move. (6) Pawn may not move to last square unless the appropriate piece is available to replace it. (7) No castling; K has one non-capturing knight move per game, but loses the right if checked. (8) R, K and Q pawn has a double initial move, provided its master piece remains at home. (9) At start, 4 or 8 non-capture moves are played by each side. (10) In a series of games the winner of most games moves first.

V.R.Tope Buddhi 1893
Draw Solution: 1.B×N K×B 2.P=B P=R 3.Bg7† K-move 4.B×R
      Modern international chess is now the norm in India, Pakistan and Bangladesh.

Isardam Chess Opposing pieces of the same type may not observe each other. Converse of Madrasi Chess.

Italian Rules Progressive Chess èProgressive chess

Janus Chess A game on a widened board with 10 files using two knighted bishops (called "Janus") placed between rooks and knights. VC article by Peter Wood VC28 1998.

Japanese Chess = Shogi.

Jetan Martian chess, on a 10×10 board, with initially: b2-i2 Panthans (move "one space forward, side or diagonal, but not backward"); a2,j2 Thoats (move "two spaces, one straight and one diagonal in any direction"); a1,j1 Warrior (moves 2 wazir steps); b1,i1 Padwar (moves 2 fers steps); c1,h1 Dwar (moves 3 wazir steps}; d1,g1 Flier (moves 3 fers steps, and may jump intervening pieces); e1 Chief (moves "3 spaces in any direction; straight or diagonal or combination", switchbacks are excluded, but it is not clear if moves such as e1-d2-d1-e2 are permitted); f1 Princess ("same as Chief, except may jump intervening pieces"). The Princess is the Royal piece, i.e. cannot move onto a threatened square. The Princess also cannot capture, and has one ten-space "escape" move at any time during the game. The game can also be won if a Chief takes a Chief, but is drawn if any other piece takes the Chief, or "when both sides are reduced to three pieces [presumably not counting Chiefs or Princesses] or less of equal value and the game is not won in the ensuing ten moves, five apiece". [Edgar Rice Burroughs The Chessmen of Mars 1922].

Kamikaze Chess A capturing piece disappears along with its captive. [P.Monreal Problème 1965] In the rex inclusive version kings cannot capture.

KNIGHTED CHESS Any variant in which pieces with added power of knight are the main feature. Names given to the pieces vary widely depending on the particular game. èBird's, Capablanca's, Carrera's games, Chancellor
      In problem chess the accepted names are K+N = centaur, Q+N = amazon, R+N = empress, B+N = princess, P+N = dragon.
      The simplest variant is to replace the queen's rook by R+N and the king's knight by B+N, so that the eight baseline pieces are all different, and each possible combination of R, B, N occurs: R+B (Q), R+N, B+N. The choice for pawn promotion may as well be restricted to composite pieces as there would be little occasion to underpromote.

Knighted Chess in Disguise. Chess in disguise played with knighted pieces.

J.D.Beasley Chessics 1977
Inverted pawn = disguised man. Inverted pieces are knighted (R+N, B+N). Who wins? Solution: White cannot win by d8-e6‡ since it is Black's turn to move. Black cannot win by 50...g1-h3† 51.Ke1 h3-g2‡, since after 50...g1-h3† White can claim a draw by the 50-move rule!
      Outline proof: Black could not have moved g8 or g7 last since this would have revealed their identities. For the rook f8 to have been identified it must have come out to h5 where the white K can check that it has neither B nor N powers. Black cannot have played 00 since black R cannot have started on h8, and he cannot have played 000 because there must have been a remaining unknown on one of b8-d8. The last pawn move must have been h7×g6.

Knight Relay Chess Knights do not capture and cannot be captured, but pass on their powers to any allied piece they "observe". Article in VC: Knight Relay Chess

Korean chess = Changgi.

Kriegspiel Requires two boards and an umpire. Each player sees only his own men. The umpire announces whether a player's attempted move is legal and whether it is a capture or check.

Leo Chess Chess with leo in place of queen; moves like queen but captures by leaping over a piece to any distance beyond alonmg queen lines. [Progressive leo chess is recommended by Paul Byway].

Losing Chess The must-capture rule applies, kings can move into check and be captured, and the objective is to lose all your pieces. Usual variants: pawn may promote to king; a stalemated (i.e. deadlocked) player wins. [In my view it is questionable whether this is a form of "chess" at all, since the king is non-royal; it is a non-chess game played with the same pieces.]

Madrasi Chess When opposing pieces of the same type (e.g. white and black rooks) observe each other they are paralysed, losing all powers except the ability to paralyse.

Magnetic Chess A player's own men are repelled, the opponent's attracted. After each move the men on the same rank or file as the moved piece are pushed or pulled as far as possible. Can be Rex exclusive or inclusive.

Maharajah and Sepoys One player has only a "maharajah" (combined queen + knight, royal) while the other has the usual 16 pieces, though in the original version the pawns do not promote. The maharajah is more difficult to catch if it is allowed to ride through check (i.e. the èAKM: non-passant rule is not in force). [E.Falkener, Games Ancient and Oriental 1892].

Malefic Circe Chess [French: Circe maléfique] A captured unit is reborn as though it belongs to the other side, though it does not change colour. (e.g. WB captured on white cell reappears c8 if vacant instead of f1).

Marseilles Chess = A form of èTwo-move chess.

Martian Chess = Jetan.

MEDIAEVAL CHESS Any of a range of chess games played throughout the world in the mediaeval period (c.ad 500 - 1500). The 8 by 8 game originated in India as Chaturanga some time before ad 550, was taken up in Persia as Chatrang, and then by the Islamic empire as Shatranj. It spread through Europe from about 1100 with minor modifications to the rules, until it metamorphosed into the modern form shortly before 1500. èChatrang, Chaturanga, Shatranj.

Mediaeval Chinese Chess The chess played in China during the Tang (618-960) and Sung (960-1279) dynasties [as reconstructed by K.Himly 1870]. It used an 11 by 11 board, with six pawns, the cannons being on the back rank next to the elephants, and the general having only one counsellor within the nine-castle. The pawn and chariot could only move forward. [Murray pp.124-5]

Messigny Chess Instead of playing a normal move, a player may exchange any two like pieces of different colours. The opponent may not immediately change them back.

Mobius Chess Chess in which the left and right sides of the board are supposed joined after a 180º twist. èCylinder chess

MODERN CHESS Any form of chess current since about ad 1500 when èMediaeval chess was modified in Europe by the introduction of the long-range bishop and queen. There was much experimentation in rules for promotion, e.p. capture and castling, and regional variations persisted until the FIDE was established in 1924. Various new-chess inventors have been tempted to appropriate the name for their inventions.

Modern Courier Chess A widened chess on a 12-file board; each side having two fers and two alibabas (called "couriers") plus associated pawns; back row arrangement RNABFQKFBANR. In place of castling, F and K (like P) have the privilege of an initial double non-capturing move; king may not use this to pass through check. [Paul Byway 1971] VC articles by Paul Byway VC8 1992 and VC27 1998.

Must-capture Chess If a player is able to make a capture then capturing is compulsory. If there is a choice of captures any one may be played. èLosing chess, Shoot chess

Mutation Chess When a capture is made (except by a king) the capturing piece changes its powers (but not its colour) to those of the captured species; queens may not give direct check; a pawn capturing on the 8th rank does not promote; popular in its progressive variant.

Nuclear Chess When a capture occurs all pieces, of any colour, on adjacent cells (i.e. a King move away) are also captured.

Nuclear Circe Chess Combination of Nuclear Chess and Circe Chess. A piece that is on its home cell next to the capture cell does not reappear.

Odds Chess Chess with the giving of odds; i.e. the stronger player doing without one or more pieces. èHandicap chess

Optional Replacement Chess A captured piece may be put back on any vacant cell; bishop only on cell of same colour; pawn not on first or last rank [J.D.Beasley British Chess Magazine 1992].

Orthodox Chess Chess according to the currently dominant rules, i.e. the FIDE Laws of Chess.

OTB Chess Over-the-board play as opposed to postal, telephone or e-mail play at a distance.

Petteia Greek game thought by some to be a precursor of chess. However the exact rules are unknown, and most sources seem to regard it as similar if not the same as the Roman game of Latrunculi.

Pin Chess Chess under the rule: Pinned men do not check. There was a sustained correspondence on the pinning rule in Westminster Papers 1872-5. 'Rusticus' (January 1872) quoted an instance from actual play. 'Civis' (February 1872) upheld the idea, while 'Suburban' negatived it humorously. 'Puzzled' (December 1873) raised it again. S.J.Stevens, City of London Chess Club (November 1875) gave a clear enunciation of the rule (which is hence sometimes known as the "Stevens Principle"). See also J.P.Taylor Chess Chips 1878.

G.F.Anderson, Fairy Chess Review August 1937
Pin chess. Mate in 2 Solution: 1.Ke3 (not check, threat 2.Kf4 mate with triple check) 1...B×e5/K×e5/K×c5 2.Ke2/Kf2/B×e7‡

Pocket Knight Chess Each player starts by putting his queen's knight to one side. This can be put on any vacant cell in place of a normal move. Variant: the pocket knight is extra to the usual forces.

PROGRESSIVE CHESS Chess in which the number of moves played per go increases by one at each turn; thus white plays one move, black two, white three, black four and so on; the èCPT: Series-play rules apply
      Almost any variant can be played in progressive form; there are several popular assizes:
      Italian rules: the exact number of moves due must be played; thus where a player can escape from check but in doing so is forced to give check before completing his full quota of moves, this counts as (italian) mate. VC articles by Peter Wood VC21 1996 and VC24 1997.
      Scotch rules: fewer moves than the full series may be played;
      English rules: as Scotch, but no piece may move twice in a sequence. The game is drawn if a player cannot complete his turn. VC article by Peter Wood VC22 1996/97.
      Logical rules: there is no castling and no double pawn move (and so no en passant capture); this can be combined with the Italian or Scotch rules; [VC18 p.179]
      Variants playable using progressive rules include: èChancellor, Circe, Cylinder, Mutation, Randomised.

RANDOMISED CHESS Any form of chess in which the initial arrangement of the backrank pieces is determined at least partly by chance.
      Fischerandom A form of randomised chess promoted by Bobby Fischer. Also played in Progressive form. Articles by Peter Wood and Malcolm Horne VC25 1997.

Reflex Chess Selfmate chess with the extra condition that either player must checkmate in one if able to do so. [Invented by B.G.Laws in 1880.]
      T. R. Dawson (Fairy Chess Review August 1948 p.100) after describing a game of Rotation chess played with C.D.Locock in November 1913 comments: "It is really unfair to quote this alone, as out of a dozen Fairy games we played at this period, this was my only win. But some readers may recall a wonderful reflex game which CDL published in the old Pittsburgh Gazette Times out of the same series." Alas we have not been able to track down the score of this game so far.

N. M. Gibbins The Problemist March 1930
Reflexmate in 2 Solution: 1.Bb1 (threat 2.Rg6 Rh7‡)
1...Ke7 2.Rb6 Rc8‡ 1...Ke8 2.Rf-d6 Rf8‡
1...R×c6 2.Rf5 R×h6‡ 1...R×f6 2.Rc2 R×h6‡

Refusal Chess At any stage a player can refuse his opponent's move, and force him to substitute another. Fool's mate: If 1.e4 f5 2.exf5 refused? plays Qh5 mate (since White will refuse 2....g6).

Replacement Chess Any captured piece is put back on the board, on any vacant cell; bishop only on cell of same colour; pawn not on first or last rank. [J.Creed FCR] èOptional replacement chess

RESHAPED CHESS Various schemes have been proposed for reshaping the chessboard, usually retaining the initial arrangement of the pieces. Article in VC: Reshaping the Chessboard

Rifle Chess Captures are made "at a distance", as if firing a bullet, the capturing piece not moving. [Invented by W. B. Seabrook, 1921, as reported by T. R. Dawson Fairy Chess Review August 1947 p.94] èShoot chess

T. R. Dawson Fairy Chess Review August 1947
Rifle chess. Mate in 2 (a) diagram, (b)WK/Q h2/g1 Solution: (a) 1.Qa2 Pb6/5 (cannot capture a6) 2.Qd5‡
(b) 1.Qa1 Pb6/5 2.Qh1‡

Rotating Centre Chess After each move the centre four cells de45 rotate; the rotation can be 90° clockwise (–) or anticlockwise (+), or a 180 half-turn. èActuated revolving centre

Rotation Chess After every Nth move-pair (the number N being fixed at the start of the game) the players change sides. Or alternatively: the board is rotated 180 degrees and 'black' makes the next move with the white men.
      T. R. Dawson (Fairy Chess Review August 1948 p.100) recalled a game under these rules, with N = 10, played with C.D.Locock in November 1913: 1.e4 e5 2.d4 e×d4 3.Bc4 Nf6 4.Nf3 Bb4† 5.c3 d×c3 6.b×c3 Bc5 7.e5 Ke7 (weakening his position in preparation for the swop-round) 8.Qc2 a6 9.00 and black (TRD) now announced a forced mate on his 7th next move: 9...Bxf2† 10.Q/R/K×f2 Rf8 now change places (reverse the board) and 11.e×f6† etc.

Scotch Chess èProgressive chess under scotch rules; not to be confused with Scottish chess, which is orthodox chess played in Scotland.

Sea Chess In which the line-moving pieces are replaced by sea pieces, which travel like riders but capture like locusts (by hopping over the victim to the first square beyond); thus we have sea-rook = "triton", sea-bishop = "sea-bee" or "nereid", sea-queen = "mermaid" [G.Brogi Chess Amateur February 1929]

Selfmate Chess The aim of each player is to get his king checkmated by the opponent. This is shown in many compositions but is probably not a practical game, since the checkmating player's pieces have to be severely restricted, and he is unlikely to cooperate. èReflex chess

Shatranj Mediaeval chess as played in the Islamic empire (also called Arab, Muslim, Islamic or Mohammadan chess). The earliest form of chess for which accurate rules are known and for which records of actual games, opening analysis, chess problems and endings survive, as played in Baghdad, the centre of the Islamic empire, in the ninth century. The Arabs acquired chess through their conquest of Persia in the decades following the death of Mohammad (ad632), and the game quickly prospered with them, perhaps in part because other games involving dice and gambling were proscribed. The Mohammedan stricture against images was complied with by using pieces of abstract design. Among the early masters was an African, Sa'id bin Jubair (665-714) who is the first known èBlindfold chess player. The famous caliph Harun ar-Rashid (763-809) is said to have favoured good players and granted them pensions. The first books on chess were written from this time on, notably by al-'Adli (fl.840), as-Suli (c.880-946) and al-Lahlaj (c.970). They do not survive complete, but extracts are quoted in manuscripts compiled later, such as that by al-Baghdadi (1140). Substantially the same game was played throughout Europe until about 1500, with only slight modifications.
      In the opening position replace queen by fers (single diagonal step) and bishops by alfils (two-step diagonal move); there is no double-step pawn move and no castling; win is by checkmate, stalemate or èBare king. According to as-Suli the values of the pieces were: Rook 1, Knight 2/3, Fers 1/3, Alfil 1/4, Pawn 1/4 on centre files to 1/8 at edge. The custom seems to have been for the two players to play a series of 12 or more opening moves to build up a battle array before engaging forces; a popular one being the Mujannah (wing) array (bishop represents alfil, queen represents fers):

Players who wish to try a game of Shatranj may get a better idea of what it was like by starting from this position instead of the usual array. [Murray History of Chess pp.167-338]

Shogi The Generals' Game = Japanese Chess. Uses a board 9 by 9. The pieces are directed tiles. When captured they become the opponent's, are turned round, and can be entered on the board again at a subsequent move (subject to restrictions). Needs a long article to fully explain. See VC2 1990, VC19 1996. There are also numerous Shogi variants.

Shoot Chess Must-capture Rifle Chess. [S.Reuben British Chess Magazine February 1990].

Ski Chess In which the line-moving pieces are replaced by ski-pieces which omit the first cell in the ride, i.e. begin with a little ski-jump. Hence ski-queen, ski-rook, ski-bishop [G.P.Jelliss Problemist 1973].

Skip Chess In which the line-moving pieces are replaced by skip-pieces which omit the first and every other odd cell in the path; thus a skip-rook is a dabbabarider, a skip-bishop is an alfilrider, and combining them gives a skip-queen which would be an alibaba-rider.

Slip Chess In which the line-moving pieces are replaced by slip-pieces which omit the second and every other even cell in the path; a slip-rook is also known as a "panda", since it makes rook moves to cells of the opposite colour; we can also define slip-bishop and slip-queen.

Sniper Chess In which the back-row pieces other than Q and K are replaced by snipers. An X/Y-sniper moves like piece X and captures like piece Y. The back-rank sequence becomes R/N, N/R, B/N, Q, K, B/R, N/B, R/B. [F. Maus 1927 who called this "Thinktank chess"] èAKM: Snipers

SPACE CHESS Any form of chess on a "three-dimensional" board; and in which the moves of the pieces other than pawns are the same in all planes (this condition distinguishes space chess from layer chess); such boards are split into layers labelled A, B, C, .. from the base upwards, the capital letter acting as the third coordinate; a move in 3D space is represented by three coordinates {r,s,t}; any 2D move can be made in 3D space in each of the three coordinate planes passing through the cell initially occupied by the moving piece; in this way each 2D piece defines a corresponding space piece; Article in VC: Space Chess. èHamburg space chess, Stereochess, AKM: Space pieces.

Stereochess [German Stereoschach] a type of èSpace chess using the normal board and opening position plus a 4-by-4-by-4 cube stacked over the middle; the pawns move as usual on the level planes but can also move upwards and downwards, either by a noncapturing orthogonal move or a capturing forward-diagonal move (maximum thus 3 travel moves and 4 captures); [Gerhard W. Jensch feenschach 1975]

Sting Chess with èscorpions (K+G) in place of kings.

"Superpins" = Pin Chess.

SYMMETRIC OPENING POSITION GAMES In which the left and right sides of the board are similarly arrayed. èShogi, Twin King Chess, Xiangqi.

Tandem Chess = Bughouse Chess.

THREE-HANDED CHESS Any variant for three players; to be a fair game it requires a specially designed board.

Three Kingdoms Game A three-handed version of Xiangqi, representing an actual "war of three kingdoms" that took place in ad 221-264; each player, blue, green and red, has his own 9 by 5 kingdom with the usual array of pieces, to which are added, at the forward corners of the nine-castle, two new pieces which move two (0,1) steps followed by one (1,1) step outwards (i.e. blockable camels; but termed chuo = fire, chi = banner or feng = wind); the three areas are arranged facing a common triangular centre, the files in each half-kingdom linking with the files in the adjacent half-kingdom; when a general is checkmated the player who gave the mate removes the general from the board and assumes command of his forces; the rules say nothing about what happens if a general is defeated by a combined action of his two opponents.

Timur's Game A form of great chess favoured by the central asian ruler Timur-i-leng (1336-1404), also known as Tamerlane, described by his biographer ben Arabshah (d.1450) and in a 16th century manuscript in the Royal Asiatic Society which may be a copy of a work on chess known to have been written by Ala'addin Tabrizi (alias Ali ash-Shatranji, i.e. Ali the chessplayer), the leading player at Timur's court. Timur's Great Chess uses a board 11 by 10 with extra squares (citadels) at the right end of each player's second rank. The opening position is diagrammed, where King, Knight, Pawn, and Rook are as usual; bishop = Alfil, right-facing knight = Camel, right-facing rook = Dabbaba, queen = Fers, inverted bishop = Talia (meaning scout but moving as Alfil or as Alfil followed by Bishop move, i.e. a Ski-bishop), inverted rook = Wazir, left-facing knight = Zurafa (meaning giraffe but moving a single step diagonally followed by a rook move of three or more steps, and blockable on any of the squares passed through).

The pawns promote only to the piece in whose file they initially stand, except for the leftmost pawn (a3/k8) which is known as the "pawn's pawn" and for which the rules are impossibly complex and probably unworkable. There are also rules that permit the king to escape mate under certain conditions by swapping places with his men. These types of rules strike me as being devised by Timur's opponents to allow the game to continue, so as to avoid being beheaded for beating the emperor!

Toral Chess Played on a torus-board, in which left and right edges are supposed joined and also top and bottom edges = combined vertical and horizontal cylinder. To avoid multiple check in the opening position special rules or a new opening position are needed.

Triplets At the firat turn each side moves a pawn, at the second a pawn and piece in either order, at the third and all subsequent moves a pawn, a piece and the king in any order. If a player cannot make any of the three moves he loses.

Twenty-first Century Chess An elaborate chess on a 10-file, 9-rank board with opening position as shown below. The back-row pieces, apart from the king, are all riders: rook, nightrider, bishop, R+NR (raven), queen, B+NR (banshee). The king is given the added power of grasshopper in place of castling and is allowed to hop through check. The second-row pieces are all hoppers, analogous to the riders in whose files they stand: rookhopper, nightriderhopper, bishopper, grasshopper, RH+NRH, BH+NRH and a lion as the king's hopper. Opting pawns are used, able to make a double step from any rank, subject to en passant capture; pawns promote on reaching either of the two back ranks of the enemy, promotion being to the rank of the piece that occupied that cell initially, except on the king cell where promotion is to Q+NR (queen of the night). To help in viewing the nightrider lines I made a board using four colours in the cells, the dark cells green and blue, the light squares yellow and orange. [G.P.Jelliss Variant Chess 1991]

Twin King Chess Starts with 2Ks on each side instead of Q and K. èCPT: multirex

TWO-MOVE CHESS Chess in which each player makes two moves (the second not the reverse of the first) at each turn of play. There are numerous different forms.
      Two-move Chess. Shinkman type The aim is checkmate, as opposed to capture of the king, but check is allowed on the first move. This can lead to unusual mates such as: W.Shinkman. Two-move chess. Mate in 1. WKh7, WQb3, WRc4; BKe5. Solution: 1.Re4†, Qe6‡ [I have this down as "in Dawson lecture, repeated by Paul Valois 25/10/96."]
      Two-move Series Chess The moves form a èCPT: series-play, that is only the last move may check the opposing king and one's own king may only be in check at the start.
      Loose Two-move Series Chess = Marseilles Chess. A player is not obliged to make his full complement of two moves.
      Strict Two-move Series Chess A player is obliged to make his full complement of moves; if unable to make two moves when so obliged the game ends and is counted stalemate or checkmate.
      Balanced Two-move Series Chess White has only one move on the first turn;
      Double-Move Chess Balanced rule applies. There is no check, the object being to capture the opponent's king.

VARIANT CHESS Any game derivable from some accepted form of chess by modification of its rules.

Vaulting Kings Chess Kings in check have extra powers of movement. This makes them more difficult to hunt or to checkmate. A wide variety of different powers have been experimented with. èAKM: Vaulting kings

Vinciperdi [Italian] = Losing chess, under the rule that a stalemated player loses.

WIDENED CHESS Any form of chess in which extra files are added to the board. It is usual to add a new piece (and pawn) for each new file. Knighted pieces are the most popular. èCarrera's game, Courier chess, Modern courier chess

Wolf Chess A 10-rank chess (8 files) using knighted rook (wolf), knighted bishop (fox). For full details see VC or ECV. [Arno von Wilpert, played 1955, published 1959]

Xadrez [Portuguese] = chess

Xiangqi Chinese chess. Played on a board 9 files by 10 ranks, with symmetrical opening position. Back row consists of two chariots a1, i1 (moving as rook). Two maos b1, h1. Two elephants c1, g1 (moving as bishop but confined to the player's own side of the board). Two guards d1, f1 (moving as fers but confined to the ninecastle def123). One general e1 (moving as wazir, but confined to the ninecastle). Two cannons (paos) b3, h3 and five Chinese pawns a4, c4, e4, g4, i4, which move and capture by a single forward step, and acquire the added ability to move and capture sideways when in the opponents side of the board. A standard Chinese work on the game The Secrets of the Orange Grove, dating from 1632, was accurately translated by W. H. Wilkinson for his Manual of Chinese Chess of 1893. Previous western accounts of the game are incomplete or inaccurate. [Murray pp.119-132]

X-ray Chess In which the line pieces are able to check (and possibly move) through occupied cells.

Yakutat Chess A form of chess played in Alaska about which little is known. VC article by Lex Kraaijeveld VC26 1997/98.

Zatrikion Greek name for Shatranj.