Luffarschack

Luffarschack is a two-player game where your object is to get five of your pieces in a row - diagonally, horizontally, or vertically - before your opponent does.

This children's game from Scandinavia has a complexity which dwarfs most two-player games; the use of ply theory is therefore impractical, and the Luffarschack engine uses an alternative method of assessing position and strategy.

The game is much more difficult than it may appear. While it is possible to beat the engine if you start play, managing a tie when the engine starts is a very good - and very grueling - effort.