Alak is a close relative of the board game Go played on a one-dimensional “board”. It was originally described in A. K. Dewdney's 1984 book The Planiverse; in 2001, Alan Baljeu modified the game to its present state.
The rules are as follows:
No stone may be placed in a location occupied by another stone, or in a location where a stone of your own colour has just been removed. The latter condition keeps the game from entering a neverending loop of stone placement and capture, known in Go as Ko.
If placing a stone causes one or two groups of enemy stones to no longer have any adjacent empty spaces–liberties, as in Go–then those stones are removed. As the above rule states, the opponent may not play in those locations on their following turn.