How to play tic-tac-toe
Two players take turns marking an empty square of a 3×3 grid, one with X and the other with O. X goes first. Three of your marks in a row, column or diagonal wins. When all nine squares are full without a line, the game is a draw.
Strategy tips
- Win first, block second: if you can complete a line, do it. If your opponent has two in a line with the third square empty, block it.
- Open in a corner or the center: the center belongs to four lines and each corner to three, so both give you more ways to win than an edge square.
- Make a fork: a move that threatens two lines at once leaves your opponent able to block only one.
- Stop forks early: when you play second against a corner opening, take the center. If your opponent then holds two opposite corners, answer on an edge, not a corner, so they have to block you.
Why the hard level never loses
Tic-tac-toe is a solved game: with best play from both sides it always ends in a draw. The hard computer works out every possible continuation (minimax) and only plays moves with the best guaranteed result, so a draw is the best you can get. Easy and Normal sometimes play a random square, which gives you a chance to win.
Many names, one game
It is called noughts and crosses in British English, tres en raya in Spain, sanmoku narabe (三目並べ) in Japan and jingziqi (井字棋) in China.