Baroque chess is a chess variant invented in 1962 by Robert Abbott. In 1963, at the suggestion of his publisher, he changed the name to Ultima, by which name it is also known. Abbott later considered his invention flawed and suggested amendments to the rules, but these suggestions have been substantially ignored by the gaming community, which continues to play by the 1962 rules. Since the rules for Baroque were first laid down in 1962, some regional variation has arisen, causing the game to diverge from Ultima.
The rules of chess govern the play of the game of chess. While the exact origins of chess are unclear, modern rules first took form during the Middle Ages. The rules continued to be slightly modified until the early 19th century, when they reached essentially their current form. The rules also varied somewhat from place to place. Today, the standard rules are set by FIDE, the international governing body for chess. Slight modifications are made by some national organizations for their own purposes. There are variations of the rules for fast chess, correspondence chess, online chess, and Chess960.
Losing chess is one of the most popular chess variants. The objective of each player is to lose all of their pieces or be stalemated, that is, a misère version. In some variations, a player may also win by checkmating or by being checkmated.
Atomic chess is a chess variant. Standard rules of chess apply, but all captures result in an "explosion" through which all surrounding white and black pieces other than pawns are removed from play. Some variations additionally remove rules concerning check such that the king may be able to move into or remain in check.
Alice chess is a chess variant invented in 1953 by V. R. Parton which employs two chessboards rather than one, and a slight alteration to the standard rules of chess. The game is named after the main character "Alice" in Lewis Carroll's work Through the Looking-Glass, where transport through the mirror into an alternative world is portrayed on the chessboards by the after-move transfer of chess pieces between boards A and B.
Progressive chess is a chess variant in which players, rather than just making one move per turn, play progressively longer series of moves. The game starts with White making one move, then Black makes two consecutive moves, White replies with three, Black makes four and so on. Progressive chess can be combined with other variants; for example, when Circe chess is played as a game, it is usually progressively. Progressive chess is considered particularly apt for playing correspondence chess using mail or some other slow medium, because of the relatively small number of moves in a typical game.
Zendo is a game of inductive logic designed by Kory Heath in which one player creates a rule for structures ("koans") to follow, and the other players try to discover it by building and studying various koans which follow or break the rule. The first student to correctly state the rule wins.
Martian Chess is an abstract strategy game for two or four players invented by Andrew Looney in 1999. It is played with Icehouse pyramids on a chessboard. To play with a number of players other than two or four, a non-Euclidean surface can be tiled to produce a board of the required size, allowing up to six players.
Forchess is a four-player chess variant developed by T. K. Rogers, an American engineer. It uses one standard chessboard and two sets of standard pieces.
Janggi, sometimes called Korean chess, is a strategy board game popular in Korea. The game was derived from xiangqi, and is very similar to it, including the starting position of some of the pieces, and the 9×10 gameboard, but without the xiangqi "river" dividing the board horizontally in the middle.
Kriegspiel is a chess variant invented by Henry Michael Temple in 1899 and based upon the original Kriegsspiel developed by Georg von Reiswitz in 1812. In this game each player can see their own pieces, but not those of their opponent. For this reason, it is necessary to have a third person act as an umpire, with full information about the progress of the game. Players attempt to move on their turns, and the umpire declares their attempts 'legal' or 'illegal'. If the move is illegal, the player tries again; if it is legal, that move stands. Each player is given information about checks and captures. They may also ask the umpire if there are any legal captures with a pawn. Since the position of the opponent's pieces is unknown, Kriegspiel is a game of imperfect information.
Four-player chess is a family of chess variants played with four people. The game features a special board typically made of a standard 8×8 square, with 3 rows of 8 cells each extending from each side, and requires two sets of differently colored pieces. The rules are similar to, but not the same as, regular chess. There are a variety of different rule variations; most variantions, however, share a somewhat similar board and piece setup.
Yonin shōgi,, is a four-person variant of shogi. It may be played with a dedicated yonin shogi set or with two sets of standard shogi pieces, and is played on a standard sized shogi board.
Three-player chess is a family of chess variants specially designed for three players. Many variations of three-player chess have been devised. They usually use a non-standard board, for example, a hexagonal or three-sided board that connects the center cells in a special way. The three armies are differentiated usually by color.
2000 A.D. is a chess variant created by V. R. Parton which employs fairy chess pieces on a 10×10 board. Parton published the variant in his 1972 monograph My Game for 2000 A.D. and After.
Dragonfly is a chess variant invented by Christian Freeling in 1983. There are no queens, and a captured bishop, knight, or rook becomes the property of the capturer, who may play it as his own on a turn to any open square. The board is 7×7 squares, or alternatively a 61-cell hexagon with two additional pawns per side.
Beirut chess is a chess variant invented by Jim Winslow in 1992. The game is played using the standard chess pieces and board, with each side having secretly equipped one of their men with a "bomb"—which can be "detonated" at any time, wiping out all men on surrounding squares along with the bomb carrier.
Apocalypse is a chess variant invented by C. S. Elliott in 1976. Each player starts with two horsemen and five footmen on a 5×5 board. The two sides make their moves simultaneously.
