List of chess variants
A chess variant (or unorthodox chess) is a game "related to, derived from or inspired by chess". The difference from chess might include one or more of the following:
different rules for capture, move order, game objective, etc.;
addition, substitution or removal of pieces in standard chess (non-standard pieces are known as fairy pieces);
different chessboard (larger or smaller, non-square board shape overall or different intra-board cell shapes such as hexagons).
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 2,000.
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.