Cubic chess is a chess variant invented by Vladimír Pribylinec beginning with an early version (named Echos) in 1977.[1][2][3] The game substitutes cubes for the chess pieces, where four of the faces of each cube display a different chess piece (pawn, knight, bishop and rook), the two other faces are blank and are orientated to the players. This provides an efficient means (rotating the cube on a square) to change a piece's type. Kings and queens have unique cubes containing only their symbol, effectively behaving as normal.
The game begins like standard chess, with a normal 8×8 chessboard, and cubes rotated so that uppermost faces reflect the standard chess starting position.
Non-pawn pieces that become captured, are retained by the capturer—unrotated—into off-board "stock".
For their turn, a player may either:
make a normal chess move using one of the pieces already on the board; or
rotate any pawn such that uppermost on the player's cube is any piece type contained in the player's "stock". A corresponding piece in the stock is immediately removed from the game.
Pritchard, D. B. (2007). "Cubic Chess [Pribylinec]". In Beasley, John (ed.). The Classified Encyclopedia of Chess Variants. John Beasley. ISBN978-0-9555168-0-1.