Hexapawn
Hexapawn is a deterministic two-player game invented by Martin Gardner. It is played on a rectangular board of variable size, for example on a 3×3 board or on a regular chessboard. On a board of size n×m, each player begins with m pawns, one for each square in the row closest to them. The goal of each player is to either advance a pawn to the opposite end of the board or leave the other player with no legal moves, either by stalemate or by having all of their pieces captured.
| a | b | c | |||
| 3 | 3 | ||||
| 2 | 2 | ||||
| 1 | 1 | ||||
| a | b | c |
Hexapawn on the 3×3 board is a solved game; with perfect play, White will always lose in 3 moves (1.b2 axb2 2.cxb2 c2 3.a2 c1#). Indeed, Gardner specifically constructed it as a game with a small game tree in order to demonstrate how it could be played by a heuristic AI implemented by a mechanical computer based on Donald Michie's Matchbox Educable Noughts and Crosses Engine.
A variant of this game is octopawn, which is played on a 4×4 board with 4 pawns on each side. It is a forced win for White.
Only 24 matchboxes are required for a hexapawn version of Matchbox Educable Noughts and Crosses Engine.