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Duel

Tic-Tac-Toe

Choose your board. Connect your line. Beat a friend, or try to draw the computer.

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About Tic-Tac-Toe

Tic-Tac-Toe, also called noughts and crosses, is the oldest duel there is: two players, X and O, take turns marking squares, and the first to line up their marks in a row, column or diagonal wins. Here you can play the classic 3×3 board or step up to 4×4 and 5×5, where you need four in a row, against the computer or a friend in another browser.

How to play

  • X moves first. Players take turns placing one mark on any empty square.
  • On 3×3, three marks in a row win. On 4×4 and 5×5, four in a row win.
  • The marks must be consecutive in a row, column or diagonal.
  • If the board fills with no winner, the round is a draw.
X wins on the top row of a legal 3 by 3 Tic-Tac-Toe position.
On the classic board, three matching marks across, down or diagonally win.

Three boards, three different games

3×3 is solved. With perfect play from both sides, every game is a draw, and the computer here plays perfectly. You cannot beat it: the challenge is never to lose.

4×4 gives you room. Four in a row on a 4×4 board means filling a whole line, so blocking is easy and long games are common.

5×5 is where tactics start. With four in a row needed and space to spare, you can build two threats at once, a fork, and the computer can only block one.

Play a friend

Choose Play with a friend, pick the board size, enter your name and create a room. Copy the link and send it. Your friend opens it in their own browser, enters a name and takes the second seat. No account is needed on either side.

A room keeps its board size and lasts 24 hours. After each round both players accept Rematch, and the first move alternates so neither of you keeps the advantage. If you refresh or lose connection, return in the same browser to get your seat back.

Play the computer

Choose Play the computer and start straight away. On 3×3 it never makes a mistake. On 4×4 and 5×5 it searches ahead to attack, block and build forks of its own. Changing the board size starts a new match.

Tips

  • On 3×3, take a corner or the centre on your first move.
  • If your opponent opens in a corner, take the centre. Any other reply can lose.
  • Look for forks: a move that makes two lines of two at once. Your opponent can only block one.
  • On bigger boards, block early. Three in a row with both ends open is already too late to stop on 5×5.
After X takes the bottom-left corner, X can win at middle-left or bottom-middle; O cannot block both.
A fork creates two winning moves at once. The highlighted squares show X’s two threats; it is O’s turn.

More in how to win at tic-tac-toe.

Scoring

Wins and draws are counted in the current match. Computer games and friend rooms keep separate scores, and duels are not ranked on a global leaderboard.

Frequently asked questions

Can you beat the computer at Tic-Tac-Toe?

Not on 3×3. It plays perfectly, so a draw is the best result. On 4×4 and 5×5 it can be beaten with a well-built fork.

How do I play Tic-Tac-Toe with a friend online?

Choose Play with a friend, create a room and send your friend the link. They join from their own browser, no account needed.

Why is Tic-Tac-Toe always a draw?

On a 3×3 board, every threat can be blocked in time if both players play correctly. Games are only won when someone misses a threat or a fork.

Who goes first?

X moves first. After each rematch the first move switches to the other player.

Is it the same as noughts and crosses?

Yes. Noughts and crosses is the British name for the same game.

From the duel guide