Tic-Tac-Toe Online
Classic tic-tac-toe in your browser: face the computer on three levels, where the last one is unbeatable, or challenge someone to a 2-player game on the same phone. Want a twist? Try the 4×4 board.
Your turn — you are X
Who starts alternates each game.
How to play tic-tac-toe
Each player has a symbol, X or O, and you take turns marking an empty square of the 3×3 board. The first to complete a line of three matching symbols, horizontally, vertically or diagonally, wins.
If all nine squares are filled without anyone making a line, it is a “cat’s game”: a draw. The scoreboard counts wins and draws, and whoever starts alternates with each new game to keep things fair.
Against the computer, choose Easy to learn, Medium for a light challenge or Unbeatable, which calculates every possible move and never loses. On the 4×4 board the rule is the same, but you must complete four in a row.
Frequently asked questions
Can I beat the computer on the unbeatable level?
No. Tic-tac-toe is a solved game: with both players playing perfectly, it always ends in a draw. The unbeatable level uses the minimax algorithm, so the best you can get is a draw, but it punishes any slip.
What is the best opening move in tic-tac-toe?
Starting in a corner is the trickiest opening: if the opponent does not answer in the center, you can usually set up a double threat and win. The center is also strong and is the safest reply when the other player starts.
Why is it called tic-tac-toe?
The best-known explanation is that in old England it was a pastime for ladies who could no longer see well enough to sew. In other countries it has other names, such as noughts and crosses, and in Spanish-speaking countries “tres en raya”.