How to play

Halma is a centuries-old board game. Many variations exist. In this example, I’ve created a solitaire version of Halma with 9 pieces on a 9 × 9 board. In the beginning of the game, the pieces form a 3 × 3 square in the bottom-left corner of the board. The object of the game is to move all the pieces so they form a 3 × 3 square in the upper-right corner of the board, in the least number of moves.

There are two types of legal moves in Halma

• Take a piece and move it to any adjacent empty square. An “empty” square is one that does not currently have a piece in it. An “adjacent” square is immediately north, south, east, west, northwest, northeast, southwest, or southeast of the piece’s current position.

• Take a piece and hop over an adjacent piece, and possibly repeat. That is, if you hop over an adjacent piece, then hop over another piece adjacent to your new position, that counts as a single move. In fact, any number of hops still counts as a single move.