Tic-tac-toe

Noughts and crosses, 1 or 2 players.

Play against
Computer
Who starts

0You (X) 0Draws 0Computer (O)

Keys 1 to 9 play the squares, top left to bottom right. N starts a new game.

Scores are kept on this device.

Runs in your browser. Nothing uploaded.

How to play tic-tac-toe

  1. Pick the computer or a friend. Against the computer, choose Easy, Medium or Unbeatable and who starts. You play X.
  2. Click a square, or press 1 to 9 on the keyboard, to put your mark there. Players take turns.
  3. Get three in a row across, down or diagonally to win. A full board with no line is a draw. Press New game for the next round.

How to win more games

  • Start in a corner. A corner gives your opponent the most chances to go wrong. Against a corner opening, the only move that holds the draw is the center.
  • Make a fork. A fork is a move that threatens two lines at once. Your opponent can block only one, so you win with the other. Medium can’t see forks coming.
  • Block first, then build. If your opponent has two in a row, block it before anything else. Then look for a square that blocks and threatens at the same time.

Why it always ends in a draw

There are 255,168 possible games of tic-tac-toe, few enough for a computer to check them all. Doing so shows that neither side can force a win, which is why the unbeatable level never loses and why games between experienced players almost always end level.