❌⭕ How to play Tic-Tac-Toe (and never lose)
By Miguel Arechaga
Tic-Tac-Toe is the first strategy game almost everyone learns. It's so small that it can be fully "solved": with the right strategy, it's impossible for you to lose. Here's how to play it and how to master it.
What is Tic-Tac-Toe?
It's played on a 3x3 grid between two players, one with X and one with O. Whoever places three of their own symbols in a row wins: horizontally, vertically, or diagonally. In our version you play as X against the computer.
How to play
- Tap an empty square to place your symbol; then the computer moves.
- Get three in a row before your opponent to win.
- If the board fills up with no line, it's a draw.
- Choose Easy (the computer sometimes makes mistakes) or Unbeatable (it never loses).
The strategy to never lose
There's a priority order that guarantees you never lose. On each turn, check in this order: first, can you win with this move? Do it. If not, can your opponent win on their next move? Block it. If there are no threats, play the center; it's the most valuable square because it's part of four lines.
The master move is creating a double threat: placing your symbol so it threatens two lines at once. Your opponent can only block one, and you win with the other. Corners are ideal for setting up these traps.
Quick tips
- If you go first, opening on a corner or the center gives more options than a side square.
- Always watch the diagonals: they're the lines people forget most often.
- Against a perfect opponent, the realistic goal is a draw; focus on never missing a block.
Master these ideas and you'll be able to take on Unbeatable mode without losing a single game.
Play online with 2 players
You can play Tic-Tac-Toe against another person in several ways: tap "🌐 Online" and create a room to share a 4-letter code with whoever you want to challenge, use "🔍 Find opponent" to get matched instantly with another available player, or add a friend by their username from the 👥 Friends panel (while logged in) and tap "Challenge" next to their name to invite them directly to a game.
🏆 Wins ranking
All your online Tic-Tac-Toe games are logged to your account: every win (and every loss) adds to your history. Go to Ranking, the 🎮 2 Players tab, choose "Tic-Tac-Toe" from the dropdown, and check your position against other players, synced across all your devices. For your results to count you need a free account on MundoSudoku (just a username and password, no email required): you can play without one, but without logging in your score won't be saved to the ranking.
