AWESOME!!
I love tic-tac-toe, and this surely makes it alot more fun! I absolutely love this game and the 4 levels of difficulty!
One of my hobbies is to play tic-tac-toe with people and show them how I never lose, but I lost to the computer and learned it's tricks, and now I have a whole new repertoire of tactics to use on defenceless non-players of this game!
What could've been better:
It would be fun with some different backgrounds instead of just that blue one, and a Song selecter would've been nice, but then again, shut off the music and play some tunes on your media player.. :P Ah, you get the point.
All in all, I gave this game a vote 5, because I really liked it and it makes good practice. But a sequel would be nice, too, if you have the time. It's very fun!