In Tic-Tac-D'oh you choose where NOT to drop your piece. The computer then randomly drops your piece on one of the remaining empty squares. X gets to drop its piece in the final empty space. As in regular Tic-Tac-Toe, you win by getting three pieces in a row.
 
The game is not (entirely) trivial. The role of chance diminishes as the board fills up. Although you need luck to win, there are strategies that maximize your odds. If 'O' survives the first seven drops, it can force the last drop, giving O an advantage in the end. Prior to that point X has the advantage.