Notakto

"Simple to learn and hard to master, Notakto is a variation on Tic-Tac-Toe where BOTH players make X's and whoever makes three-in-a-row LOSES.

Difficulty ranges from Easy to Insane. At Insane, the computer uses advanced game theory techniques to play a perfect game, so don't make any mistakes if you want to win!

Unlock all levels and play on up to six boards at the same time!

Choose Rated Play and work toward becoming Notakto World Champion.

Reviews:

***** Fun and addictive! - This game is ingenious and fun!

***** Outstanding - Brilliant app. It's amazing how taking away a symbol and reversing the win condition can turn a trivial game into a fiendishly difficult addiction."

Counterwave, Inc.