DIM

Equipment: A number of counters (or coins or matches or any small objects)

Number of players: 2

The Set-up: The counters are arranged into several 'heaps'. Here is a typical three-heap game:

A Move: At your turn you may remove d counters from a heap of size n only if d divides n.

You win: If your opponent has no valid move.

Comments: In the game above the following are legal moves for the opening player: From Heap 1 remove 1, 2, 4 or 8 counters. From Heap 2 remove 1, 2, 3 or 6 counters. From heap 3 remove 1 or 5 counters.

Variations: In the above description of the game, removing n counters from a heap of size n is a legal move. There is a variation, called Dim-, that makes this move illegal.