Your turn — place an X
XO Pro is a free online Tic Tac Toe game you can play instantly in your browser — no download and no sign-up. Take on a smart computer opponent across three difficulty levels, or switch to two-player mode and share one screen with a friend. Every round keeps score of your wins, losses and draws, and the clean fullscreen board keeps the focus on the game whether you are on a phone, tablet or desktop.
The rules are simple. Players take turns marking squares on a three-by-three grid, X against O. The first player to line up three of their marks in a row — horizontally, vertically or diagonally — wins the game. If all nine squares fill up and nobody has three in a row, the round is a draw. In XO Pro you always play as X and move first, while the computer answers as O. In two-player mode you and a friend simply alternate turns on the same device, and the scoreboard tracks the whole session.
Winning at Tic Tac Toe comes down to a few reliable habits. Taking the center square on your first move is the strongest opening, because the center touches four of the eight possible winning lines — more than any corner or edge. Corners are the next best choice, since each corner sits on three winning lines. Always look for a chance to create a "fork": if a single move threatens to complete two different lines at once, your opponent can only block one of them and you win on the next turn. Just as important, watch your opponent closely — the moment they get two marks in a row, block the open end before they can finish.
On the Impossible difficulty the computer uses a minimax algorithm that looks ahead through every possible sequence of moves, so it plays a mathematically perfect game and can never be beaten — the very best you can force against it is a draw. That makes it a great way to sharpen your own play. Drop the difficulty to Easy or Medium for a more relaxed match where the computer sometimes slips up and a clean win is well within reach. Ready to test your strategy? Take the center square and make your first move.