Tic-Tac-Toe

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Tic-Tac-Toe

Play against the computer or with a friend, right in your browser

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  • Runs in your browser
  • No signup
  • Games
  • Updated on
About this tool

The classic tic-tac-toe, with a real AI

Tic-tac-toe (noughts and crosses) is the classic pen-and-paper game where two players take turns marking X and O on a 3×3 board, trying to line up three of their symbols. This online version lets you play against the computer at three levels or against a friend on the same device. On the impossible level, the machine uses the minimax algorithm with alpha-beta pruning, it plays perfectly and never loses, at most it draws. On easy and medium it makes deliberate mistakes to give you a chance. The score is saved in your browser and the winning line is highlighted automatically.

How to use

Pick a mode and play

  1. Choose to play against the computer (and the difficulty) or in 2-player mode.
  2. Tap an empty cell to place your symbol, you always start as X.
  3. Line up three symbols to win; use "Play again" for the next round and watch the scoreboard.
FAQ

Frequently asked questions

No. On impossible the machine uses the minimax algorithm, which evaluates every possible move and always picks the best one. Against perfect play the best you can get is a draw, winning is impossible, hence the level's name.

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