What you need
Two players, a pencil and a 3×3 grid: two vertical lines crossed by two horizontal lines, giving nine squares. You can draw it anywhere, from a napkin to a whiteboard. Our printable tic-tac-toe sheet has 12 empty grids, enough for a car trip or a rainy break. In Britain and the Commonwealth the game is called noughts and crosses.
Setup
Draw the grid. One player takes X, the other O. Decide who starts: there is no fixed rule, but most people let X go first and swap who starts after each game, because starting is a small advantage.
How to play
- The first player writes their mark in any empty square.
- The second player writes theirs in another empty square.
- Players keep alternating, one mark per turn. You cannot skip a turn or write in a square that is already filled.
- As soon as a player has three of their marks in a line, across, down or diagonally, the game stops.
Scoring and winning
The first player to complete a line of three wins and traditionally draws a line through it. If all nine squares are filled with no line of three, the game is a draw.
Tic-tac-toe is a solved game: if both players make no mistakes, every game ends in a draw. That is exactly why it is good for children, who are still discovering the patterns. For a match, play an agreed number of games and count wins.
Common variants
- Misère tic-tac-toe: the player who makes three in a row loses. Still a draw with perfect play, but it makes everyone think backwards.
- Bigger boards: on a 4×4 grid you need four in a row; on large paper grids, five in a row is the classic game of gomoku.
- Numerical tic-tac-toe: invented by the mathematician Ronald Graham. One player writes odd numbers 1 to 9, the other even numbers, each used once; the first to complete a line adding up to 15 wins.
- Wild tic-tac-toe: on each turn you may write either an X or an O; whoever completes any line of three of the same mark wins.
- 3D tic-tac-toe: on a 3×3×3 cube drawn as three stacked grids, the first player wins easily by taking the centre. The 4×4×4 version, Qubic, is a real challenge.
Tips for first games
- If you go first, start in a corner or the centre. A corner start gives the other player the most chances to go wrong, because you can aim for two threats at once (a fork), which wins.
- If your opponent starts in a corner, take the centre. If they start in the centre, take a corner.
- On every turn check in this order: can I complete a line now? Must I block a line of two? Can I make a fork, or must I stop one?
- After a few games, teach children to look for forks. Once both players block every fork, they have found the draw.
Frequently asked questions
Who goes first? Any agreed way. Most people let X start and alternate the first player each game.
Can you always win if you go first? No. With perfect play by both players the game is a draw. Going first only gives more chances to profit from mistakes.
Is a diagonal line a win? Yes. Three in a row counts across, down or along either diagonal.
What is the best first move? A corner or the centre. A corner start sets the most traps for an opponent who replies on an edge.
How long does a game take? Under a minute, so most people play several in a row.
