Tic Tac Toe
The classic game of Xs and Os: challenge the computer or play with a friend on the same screen. You play X and go first; the winning line lights up.
Tic-tac-toe is a "solved" game: perfect play never loses
There are only a few thousand possible games, and mathematicians have analyzed every one of them: if both players always make the best move, tic-tac-toe inevitably ends in a draw. Going first still gives you a practical edge, though — opening in a corner is the trickiest choice, because your opponent can only hold the draw by answering in the center. The computer on this page follows the classic strategy: it completes its own line when it can, blocks yours, then grabs the center and corners. Beating it means setting up a double threat.
The winning trick: the fork (double threat)
The only way to beat an attentive opponent is to create a fork: two open lines you could complete on the same turn, so a single block is never enough. The classic setup is taking two opposite corners through the center, or two corners along the same edge. If your opponent is the one threatening a fork, the right defense is usually a counterattack: create a threat they must block, forcing them to abandon their plan.