Tic-Tac-Toe
Classic noughts and crosses against the computer or a friend.
How to use: Pick an opponent, then tap a square to place your X. Get three in a row to win.
How to play Tic-Tac-Toe
Tic-tac-toe, also known as noughts and crosses, is played on a three-by-three grid. Two players take turns marking a square with X or O, and the first to line up three of their marks in a row, column or diagonal wins. If the grid fills with no winner, the game is a draw.
Choose a mode from the menu. Against the unbeatable computer you play X and move first. The computer uses the minimax algorithm, which looks at every possible future move, so the best you can do is draw. Against the easy computer it picks random squares, giving you a chance to win. The two-player mode lets two people share one device. A scoreboard tracks wins and draws until you reload the page.
A few tips: taking the centre or a corner on your first move gives you the most options, and if your opponent takes the centre, a corner reply is safest. Look for forks, where one move creates two threats at once, because your opponent can only block one. Perfect play from both sides always ends in a draw, which is why the game is a good first lesson in game theory.
The game works with a mouse, a finger or a keyboard using Tab and Enter, and it runs entirely in your browser.
Frequently asked questions
Can the computer be beaten?
In unbeatable mode, no: the best result against perfect play is a draw. Try the easy mode to win.
Who goes first?
You always play X and move first. In two-player mode X starts.
Can I play with a friend?
Yes. Choose the two-player mode and take turns on the same screen.