Terraprint

Grant Acedrex Chess

Grant Acedrex is a medieval Spanish great chess variant played on a 12x12 board. It features several unique pieces with powerful movesets. It is described in the 1286 manuscript Libro de los Juegos (Book of Games) commisioned by King Alfonso X of Castille, Galicia, and Leon.

Pieces & Movesets

The rook, king, and pawn move as in modern chess. There is no pawn double jump or en-passant, though to speed up the game pawns start on the fourth rank.

A Cockatrice or Crocodile moves as the modern chess bishop. That is it may move diagonally any number of squares.

Cockatrice (Crocodile)

A Giraffe moves as a 3,2 leaper.

Giraffe

A Lion moves as a 3,0 and 3,1 leaper.

Lion

An Aanca or Great Bird moves 1 space diagonally and then optionally continues moving along a straight line as a rook away from where its move started.

Aanca (Great Bird)

A Unicornio or Rhino moves as a modern chess knight then continues diagonally away from its start position.

Unicornio (Rhino)

Starting Array

A Grant Acedrex set in starting array on a 12x12 board.

Starting Array

Pawn Promotion

Pawns are immediately promoted to whichever piece starts the game in the file they promote on. If the pawn promotes on the king's file (G) then it promotes to an Aanca.

Dice

Dice may be used to speed up the game by limiting which piece a player may move on their turn. One 8 sided die is used. Each number corresponds to a piece:

  1. Pawn
  2. Giraffe
  3. Cockatrice (Crocodile)
  4. Lion
  5. Rook
  6. Unicornio (Rhino)
  7. Aanca (Great Bird)
  8. King
Multiple 8 sided dice could be used to give players limited, but not fully restricted, choice of piece. The historical game only uses one 8 sided die.

Win Condition

A player wins by either checkmating, stalemating, or baring the opponent's king.

Artist Credits

The heraldric animals used for the Aanca, Lion, Cockatrice (Crocodile), Giraffe, and Unicornio (Rhinoceros) are not my own design but are taken from SVG files created by talented artists and made freely available to me on condition of attribution. Thanks to these artists:

See Also

Diagrams Created With Musketeer Chess Board Painter