Here's my Tic-Tac-Toe game for TI-Concours part one.
It features two levels of AI (easy and hard), which you can use for either player, or both.
It also saves three games at a time, so if you quit from them early you can continue playing, or you can use them as replays for studying your moves, if you ever need to do that.
Here it is running on an 83PSE: