Tic-tac-toe is a fun game that you can play any time and anywhere as long as you have a piece of paper, a pencil, and an opponent. Tic-tac-toe is a zero-sum game, which means that if both players are playing their best, then neither player will win. However, if you learn how to play tic-tac-toe and master some simple strategies, then you'll be able to not only play but win the majority of the time.