Tic-tac-toe: rules and strategy
The rules, the opening, forks, and why perfect play is a draw.
Rules
Two players take turns marking an empty square of a 3×3 grid: one plays X, the other O. Three of your marks in a row, column or diagonal wins. A full board without a line is a draw. On MAK Games, who starts is random.
Strategy
- Win if you can complete a line.
- Block if your opponent can complete one.
- Fork: make a move that creates two ways to win at once. Your opponent can only block one.
- Block their fork, ideally by forcing them to respond to your own threat.
- Otherwise take the centre, then a corner (especially the one opposite your opponent's), then an edge.
Openings
- Going first, a corner sets the most traps. If the opponent answers on an edge or the opposite corner, you can usually force a fork.
- Going second, answer a corner with the centre. Answer the centre with a corner.
Perfect play
With perfect play from both sides, every game is a draw. That's why the hard bot can't be beaten: the best you can do is draw. The casual bot sometimes plays a random square; that's your chance to set up a fork.
Practice game
Play a practice game right here, against bots where the game has them (or play every seat yourself). Nothing is saved.
Ready to try it?
Play Tic-tac-toe