Grant Acedrex

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12a12 black rookb12 black championc12 black unicornd12 black giraffee12 black bishopf12 black wizardg12 black kingh12 black bishopi12 black giraffej12 black unicornk12 black championl12 black rook12
9a9 black pawnb9 black pawnc9 black pawnd9 black pawne9 black pawnf9 black pawng9 black pawnh9 black pawni9 black pawnj9 black pawnk9 black pawnl9 black pawn9
4a4 white pawnb4 white pawnc4 white pawnd4 white pawne4 white pawnf4 white pawng4 white pawnh4 white pawni4 white pawnj4 white pawnk4 white pawnl4 white pawn4
1a1 white rookb1 white championc1 white unicornd1 white giraffee1 white bishopf1 white wizardg1 white kingh1 white bishopi1 white giraffej1 white unicornk1 white championl1 white rook1
Grant Acedrex, starting position
From left to right, the pieces on the back rank are: rook, lion, unicornio, giraffe, crocodile, aanca, king, crocodile, giraffe, unicornio, lion, rook.

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 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.


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.


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].

12a12b12c12d12e12 up arrowf12g12 up arrowh12i12j12k12l1212
11a11b11c11d11e11 up arrowf11g11 up arrowh11i11j11k11l1111
10a10b10c10d10e10 up arrowf10g10 up arrowh10i10j10k10l1010
9a9b9c9d9e9 up arrowf9g9 up arrowh9i9j9k9l99
8a8b8c8d8e8 up arrowf8g8 up arrowh8i8j8k8l88
7a7 left arrowb7 left arrowc7 left arrowd7 left arrowe7 black circlef7g7 black circleh7 right arrowi7 right arrowj7 right arrowk7 right arrowl7 right arrow7
6a6b6c6d6e6f6 white wizardg6h6i6j6k6l66
5a5 left arrowb5 left arrowc5 left arrowd5 left arrowe5 black circlef5g5 black circleh5 right arrowi5 right arrowj5 right arrowk5 right arrowl5 right arrow5
4a4b4c4d4e4 down arrowf4g4 down arrowh4i4j4k4l44
3a3b3c3d3e3 down arrowf3g3 down arrowh3i3j3k3l33
2a2b2c2d2e2 down arrowf2g2 down arrowh2i2j2k2l22
1a1b1c1d1e1 down arrowf1g1 down arrowh1i1j1k1l11
Move of the aanca


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].

12a12 up-left arrowb12c12d12e12f12g12h12i12j12k12 up-right arrowl1212
11a11b11 up-left arrowc11d11e11f11g11h11i11j11 up-right arrowk11l11 up-right arrow11
10a10 up-left arrowb10c10 up-left arrowd10e10f10g10h10i10 up-right arrowj10k10 up-right arrowl1010
9a9b9 up-left arrowc9d9 up-left arrowe9f9g9h9 up-right arrowi9j9 up-right arrowk9l99
8a8b8c8 up-left arrowd8e8 black circlef8g8 black circleh8i8 up-right arrowj8k8l88
7a7b7c7d7 black circlee7f7g7h7 black circlei7j7k7l77
6a6b6c6d6e6f6 white unicorng6h6i6j6k6l66
5a5b5c5d5 black circlee5f5g5h5 black circlei5j5k5l55
4a4b4c4 down-left arrowd4e4 black circlef4g4 black circleh4i4 down-right arrowj4k4l44
3a3b3 down-left arrowc3d3 down-left arrowe3f3g3h3 down-right arrowi3j3 down-right arrowk3l33
2a2 down-left arrowb2c2 down-left arrowd2e2f2g2h2i2 down-right arrowj2k2 down-right arrowl22
1a1b1 down-left arrowc1d1e1f1g1h1i1j1 down-right arrowk1l1 down-right arrow1
Move of the unicornio


  • 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 HL.
9a9b9c9d9e9 black circlef9 black circleg9 black circleh9i9j9k9l99
7a7b7c7 black circled7e7f7g7h7i7 black circlej7k7l77
6a6b6c6 black circled6e6f6 white championg6h6i6 black circlej6k6l66
5a5b5c5 black circled5e5f5g5h5i5 black circlej5k5l55
3a3b3c3d3e3 black circlef3 black circleg3 black circleh3i3j3k3l33
Move of the lion


  • The giraffe moves like a zebra, a (3,2)-leaper. (In Murray's translation, it is a (4,1)-leaper.) Its Betza notation is J.
9a9b9c9d9 black circlee9f9g9h9 black circlei9j9k9l99
8a8b8c8 black circled8e8f8g8h8i8 black circlej8k8l88
6a6b6c6d6e6f6 white giraffeg6h6i6j6k6l66
4a4b4c4 black circled4e4f4g4h4i4 black circlej4k4l44
3a3b3c3d3 black circlee3f3g3h3 black circlei3j3k3l33
Move of the giraffe


  • The crocodile moves like the modern bishop. Its Betza notation is B.



  • The pawn moves like the modern pawn, but cannot make an initial double step or capture en passant. Its Betza notation is mfWcfF. When it reaches the other end of the board (the twelfth rank for White, or the first rank for Black), it promotes to the piece that was originally there: the exception is that a pawn promoting on the g-file becomes an aanca. For example, a pawn promoting on the a-file would become a rook.

Game end[edit]

In Grant Acedrex, a player wins by either checkmating or stalemating the opponent. A player can also win by capturing all the opponent's pieces leaving them with a bare king.

Using dice[edit]

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

Computer engines[edit]

The multi-variant Chess engines Fairy-Max and Postduif can play Grant Acedrex under the XBoard or WinBoard user interface.[2][3][4]


  1. ^ Pritchard, D. B. (1994). "Grande Acedrex". The Encyclopedia of Chess Variants. Games & Puzzles Publications. p. 130. ISBN 0-9524142-0-1. Game could be played with an eight-sided die.
  2. ^ "Fairymax". Debian Manpages. Retrieved 2022-02-13.
  3. ^ Glebbeek, Evert. "Chess (Jazz & Sjaak) home". Eglebbk. Retrieved 2022-02-13.
  4. ^ "Fairy-Max". HCC Netnet. Retrieved 2022-02-13.


External links[edit]