Grant 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.

Rules

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.

King

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 in addition to its normal moves.

Aanca

The aanca moves one square diagonally, before optionally continuing orthogonally outward any number of squares. Its Betza notation is t.

Unicornio

The unicornio moves like a modern knight, before continuing diagonally outward any number of squares. Its Betza notation is t.

Lion

  • The lion moves like a threeleaper or a camel, and can jump -leaper and. Its Betza notation is HC.

    Giraffe

  • The giraffe moves like a zebra, a -leaper. Its Betza notation is Z.

    Crocodile

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

    Rook

  • The rook moves like the modern rook. Its Betza notation is R.

    Pawn

  • 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, 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

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

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, aanca, unicornio, rook, lion, crocodile, giraffe, and pawn.

Computer engines

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