* Game Center support with network gaming, leaderboards and achievements!
* Social media integration (Facebook, Twitter etc.)
* Play against your iDevice or against a friend.
* Unlimited undo.
* Saves statistics of all games. Network gaming also saves ELO ratings.
* Computer difficulty range between 1 and 9. Can run in the background.
Difficulty level 1 provides a pretty good opponent. Difficulty 9 provides an outstanding opponent. Be warned though, the higher level you choose, the more time the computer takes to think.
At level 6-7 it is only a few seconds on an iPhone 4, but level 8 may take up to 20 seconds, and level 9 may take up to 70 seconds. On older devices it will of course be even slower.