Three-Man Chess castling, a pawn's initial two-step option, "en passant", and promotion. The first player to checkmate an opponent wins the game. A player who is stalemated loses his turns to move, unless/until an opponent plays a move that releases the stalemate condition. While stalemated, his king is still subject to checkmate, and his other pieces are still subject to capture. Bibliography Three-Man Chess Three-Man Chess is a chess variant for three players invented by George R. Dekle, Sr. in 1984. The game is played on a hexagonal board comprising 96 quadrilateral cells. Each player controls a standard army of chess pieces.
Pocket Mutation Chess chess. Instead of moving, a player can take one of their own pieces from the board and put it into the pocket, provided that the pocket is empty. If the piece is placed into the pocket from the last rank, it gets promoted to a piece of higher class. Otherwise the player has an option to mutate the piece into a different piece of the same class. The choice of mutating (or not) must be made at the time the piece is removed. White cannot use the pocket on the first move. The king cannot be placed into the pocket.