Unspoiling Halma

Monday, 9th June 2014

When playing Halma by the original rules, it is possible to ruin the game for the opponents by adopting a spoiling strategy. The game's designers in the 1880s didn't think it necessary among civilised people to add rules against unsportsmanlike play. In fact, they probably didn't even consider the possibility of it happening. But modern concerns and tournament play have induced people in recent years to recognise the spoiling strategy and to guard against it.

The object of the game is to move your pieces to occupy the area in which the opposite player's pieces started. The spoiling strategy involves the spoiler leaving pieces in his starting area through the whole game, preventing his opponent from achieving his objective. It is a spoiling strategy in that by doing so, the spoiler cannot himself win the game.

One attempt at a solution modifies the conditions of victory slightly. Now, instead of winning a game by occupying your opponent's starting positions, you need only occupy those positions which he is not still occupying himself. This has the advantage, compared to some other ideas mentioned below, that it doesn't modify the character of the game at all for players not wishing to spoil it. Such players may continue to move their pieces just as they did before. But the determined spoiler can still evade this attempt to restore the game. Leaving six pieces at home, in squares A2, A3, B1, B2, C1 and C3 creates a fortress which prevents the opponent ever landing a piece in A1.

Other attempts to make rules against spoiling change the character of the game and rule out some legitimate tactics and strategies. One rule states that, while a player still has pieces in his starting area, his next move must be to move a piece out of his starting area. This will clear the starting area and prevent the spoiling. But a perfect legitimate strategy in the first few moves is to construct with a few pieces a "ladder" over which other pieces may jump to achieve long-distance moves in a single turn: this is made impossible if only pieces in the starting area may be moved at first.

Another rule change is to disallow backward moves and jumps as in draughts. This also works in that, once all the other pieces have reached the end of the board, the spoiling pieces are then obliged to move. But backward jumps and moves are sometimes legitimately used: some long and complicated ladders often involve jumps in a number of different directions to convey pieces quickly towards their proper destination.

A final proposal, then, is that a player wins the game when further forward movement of any of his pieces is impossible due to blockages in his opponent's starting area. He is as far forward as his opponent will allow him to go. In this way the character of the original game is not changed for honest players, while a spoiling strategy will not prevent an opponent from winning by legitimate play.

These ideas are also relevant to halma's derivative games of grasshopper and Chinese checkers. Any thoughts on the proposed solution are welcome by email!