This is a list of chess variants. Many thousands of variants exist. The 2007 catalogue The Encyclopedia of Chess Variants estimates that there are well over 2,000, and many more were considered too trivial for inclusion in the catalogue.
Contemporary chess variants
The chess variants listed below are derived from chess by changing one or more of the many rules of the game. The rules can be grouped into categories, from the most innocuous (starting position) to the most dramatic (adding chance/randomness to the gameplay after the initial piece placement). If a variant changes rules from multiple categories, it belongs to the sub-section below corresponding to the later-listed category. Starting position and armies Piece types Midgame rules and end-of-game rules Board shape Number of players Use of hidden information or chance.
Names that represent a set of variants are annotated with "[multivariant]" after their name.
Variant starting position (rectangular board, standard piece types and rules) Many variants employ standard chess rules and mechanics, but vary the number of pieces, or their starting positions. In most such variants, the pawns are placed on their usual squares, but the position of other pieces is either randomly determined or selected by the players. The motivation for these variants is usually to nullify established opening knowledge. The downside of these variants is that the initial position usually has less harmony and balance than the standard chess position.
Fixed positions
Active Chess [9x8]: Played on a 9×8 board, adding a queen with an extra pawn in front. Invented by G. Kuzmichov (1989), whose students tested the game, deciding that the optimal starting position was to place the second queen on the eighth or ninth files. Displacement chess [8x8, multivariant]: Some pieces in the initial position are exchanged but the rules remain exactly the same. Some examples of this may be that the king and queen are flipped, or the knight on the b-file is traded with the bishop on the f-file.
Double Chess: Two full armies per side on a 12×16 board, the first to mate an enemy king wins. Pawns advance up to four steps on their first move. Capablanca found the game "remarkably interesting". Invented by Julian Hayward (1916). Doublewide chess [16x8]: Two regular chessboards are connected for a 16×8 play surface. Each player plays with two complete sets of chess pieces. Endgame chess (or The Pawns Game, with unknown origins) [8x8]: Players start the game with only pawns and a king. Normal check, checkmate, en passant, and pawn promotion rules apply. Los Alamos chess (or Anti-Clerical chess) [6x6]: Played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. Upside-down chess [8x8]: The white and black pieces are switched so that White's pieces are on the 8th rank, with pawns on the 7th rank, one step away from promotion. The starting position looks like a standard chess starting position, but from the other player's perspective. As the pawns are blocked by pieces in the starting position, the game always starts with a knight move, and smothered mates are common.
Player-chosen positions
Polgar reform chess [multivariant]: In his book Reform-Chess (1997), László Polgár proposed several variants played on board of size 5×8, 6×8, 8×6, or 9×6. The initial piece setup is determined by players in the same way as in Benko's Pre-chess. There are special rules for castling depending on the board. Polgár recommended these variants to train creativity and to speed up the game. Pre-chess: The game starts with white and black pawns set as usual, but the initial position of other pieces is selected by the players. White first places one of their pieces on their first rank, and then Black does the same. Players continue to alternate in this manner until all pieces have been placed, with the only restriction being that bishops must be on opposite-colour squares. The game then proceeds in the usual way. Proposed by Pal Benko in 1978.
Random positions
Fischer Random Chess (or Chess960): The placement of the pieces on the first rank is randomized; although there are rules such as the 2 starting Bishops have to be on different colour squares, and the King has to start between the 2 Rooks. The opponent's pieces mirror it. Invented by Bobby Fischer (1996). Transcendental Chess: Similar to Chess960, but the opening white and black positions do not mirror each other.