Grant Acedrex starting position. From left to right, back rank pieces are: rook, lion, unicornio, giraffe, crocodile, aanca, king, crocodile, giraffe, unicornio, lion, rook.
The following rules are from the reconstruction given on the website of Jean-Louis Cazaux, based on work by him and Sonja Musser. The game is played on a 12×12 board.
Kingedit
The king moves as like modern king. Its Betza notation is thus K. Castling does not exist in Grant Acedrex. However, on its first move, a king may make a diagonal or orthogonal leap of two squares (Betza notation AD) in addition to its normal moves.
Aancaedit
The aanca (a beautiful and fearsome bird, very similar to a roc, sometimes translated incorrectly as gryphon) moves one square diagonally (like a ferz), before optionally continuing orthogonally outward any number of squares. Its Betza notation is t[FR].
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Move of the aanca
Unicornioedit
The unicornio (the illustration on the medieval codex shows a rhinoceros's head) moves like a modern knight, before continuing diagonally outward any number of squares. (In H. J. R. Murray's translation, its first move is a non-capturing knight move, after which it acts as a bishop for the rest of the game.) Its Betza notation is t[NB].
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Move of the unicornio
Lionedit
The lion moves like a threeleaper or a camel, and can jump (a combined (3,0)-leaper and (3,1)-leaper). (In Murray's translation, it can only move as a threeleaper.) Its Betza notation is HC.
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Move of the lion
Giraffeedit
The giraffe moves like a zebra, a (3,2)-leaper. (In Murray's translation, it is a (4,1)-leaper.) Its Betza notation is Z.
