Chess variant
A chess variant is a game related to, derived from or inspired by chess.[1] The difference from chess might include one or more of the following: different board (larger or smaller, non-square board shape overall or different intra-board cell shapes such as triangles or hexagons); addition, substitution or removal of pieces in standard chess (non-standard pieces are known as fairy pieces); different rules for capture, move order, game objective, etc. Regional chess games, some of which are older than Western chess, such as chaturanga, shatranj, xiangqi and shogi, are typically called chess variants in the Western world. They have some similarities to chess and share a common game ancestor. The number of possible chess variants is virtually unlimited. Confining the number to published variants, D. B. Pritchard, author of The Encyclopedia of Chess Variants, estimates there are well over 2000.[2][note 1] In the context of chess problems, chess variants are called fantasy chess, heterodox chess or fairy chess. Some chess variants are used only in problem composition and not in actual play. In these variants, the starting position is different, but otherwise the board, pieces and rules are the same. In most of such variants the pawns are placed on their usual place, but position of other pieces is either randomly determined or selected by the players. The motivation for these chess variants is to nullify established opening knowledge. The downside of these variants is that the initial position has usually less harmony and balance than standard chess position.[3 Chess960 (or Fischer Random Chess): the placement of the pieces on the first rank is randomised, and the pieces on the eighth rank mirror it. Displacement chess: 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. Pre-Chess: proposed by Pal Benko in 1978.[4] The game starts with white and black pawns set as usual, but the initial position of other pieces is selected by the players in the following way: First, White places one of his pieces on his first rank, and then Black does the same. Players continue to alternate in this manner until all pieces have been placed. (The only restriction being, bishops must be placed on opposite-colour squares.) Then the game proceeds in the usual way. Castling is permitted only if the king and a rook were placed on their usual squares. Transcendental chess: similar to Chess960, but the opening white and black positions do not mirror each other. Upside-down chess: the black and white pieces are switched so that all the pawns are one step away from promotion.[5] The game can start, for example: 1.Nc6 Nf3 2.b8=Q g1=Q etc.