The players take turns in colouring regions on a map, such that two adjoining regions cannot be different colours.
One of the players first draws a map consisting of a number of adjoining regions. The players then take turns in colouring a region, the first player using blue and the second player using red, with the restriction that two regions sharing a border cannot be different colours.
The first player unable to move loses.
In the following game the first player, Blue, is unable to move after the fourth round, and so Red wins: