Get three in a row — across, down or diagonally. You are X and move first.
Your turn (X)
How to play Tic-Tac-Toe
Players take turns marking X and O on a 3×3 grid. The first to line up three of their marks in a row — horizontally, vertically or diagonally — wins. If the grid fills with no line, it's a draw. On Hard the computer plays perfectly, so the best you can do is force a draw.
No. Against perfect play, Tic-Tac-Toe is a draw — neither player can force a win. You can only win if your opponent makes a mistake.
What is the best first move?
Taking a corner or the centre is strongest. A corner gives your opponent the most ways to slip up, while the centre touches four of the eight winning lines.
Is the Hard computer beatable?
No. On Hard the computer uses a perfect minimax strategy and never makes a mistake, so the best result you can get is a draw. Try Easy or Medium for a winnable game.
How many possible games of Tic-Tac-Toe are there?
Counting every sequence of moves, there are 255,168 possible games. Treat rotations and reflections of the board as the same, and that collapses to 26,830 games across just 765 essentially different positions — small enough that computers, and patient humans, can analyse the game completely.
Is Tic-Tac-Toe connected to magic squares?
Yes, in a lovely way. Tic-Tac-Toe is mathematically identical to a number game: two players take turns picking numbers from 1 to 9, trying to collect three that add up to 15. Arrange 1–9 in a 3×3 magic square — every row, column and diagonal summing to 15 — and the two games map onto each other exactly.
How should I respond if my opponent opens in a corner?
Take the centre — it is the only reply that holds the draw against perfect play. Answering a corner opening with an edge or another corner lets a skilled opponent force a double threat you cannot block. Once you have the centre, stay alert for forks rather than only blocking the obvious line.