Grande Acedrex

Grant Acedrex is a medieval chess variant dating back to the time of King Alfonso X of Castile. It appears in the Libro de los juegos of 1283.

The following rules are from the reconstruction of Jean-Louis Cazaux and Sonja Musser. The game is played on a 12×12 board.

Castling does not exist in Grant Acedrex. On its first move, however, a king may make a diagonal or orthogonal leap of two squares (Betza notation AD) in addition to its normal moves.

The game could be sped up by using octahedral dice to dictate which piece could move that turn, ranking them in the order: king (8), aanca (7), rhinoceros (6), rook (5), lion (4), crocodile (3), giraffe (2), and pawn (1).

The multi-variant Chess engines Fairy-Max and Postduif can play Grant Acedrex under the XBoard or WinBoard user interface.

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