Reversi, the classic strategy board game played with pieces that are dark on one side and light on the other.
A prime example of simple rules but deep strategy. You can learn how to play it in few minutes but expend many years to master it.
Improve your skill playing against Catta (the featured AI engine with 8 levels of strength) and see your progress in the statistics table.
Then challenge your friends, playing using your phone or tablet as a board.
Screen rotation is supported.