The game every kid learns first
Three-by-three grid, X against O, first to line up three wins. Americans play it on diner placemats and the backs of homework; in Britain it goes by noughts and crosses. A drawn game even has its own nickname in the US — a “cat’s game.” In 1952 it became one of the first video games (OXO, on Cambridge’s EDSAC), and in the 1983 film WarGames a computer learns from it that some games can’t be won.
That last point is the real hook. With perfect play from both sides, every game ends in a draw. So you don’t win by knowing a secret move — you win by staying sharp longer than your friend and setting traps they walk into.
How our version works
- Classic 3×3 board. Players take turns placing one mark in an empty square.
- X always moves first. A coin flip decides who starts the first game, and whoever starts plays X.
- Three of your marks in a row — across, down or diagonally — wins the game, and the winning line lights up.
- Board full with no line? That’s a draw, and it doesn’t count toward the series.
- The loser of each game moves first in the next one; after a draw the first move passes to the other player. The next game starts on its own after 3 seconds.
- A match is a series: the first player to win 5 games takes it.
- You get 30 seconds per move. Run out and the server drops your mark on a random empty square.
Play online with a friend in seconds
Tap Create, type a nickname, and your room is live. Text your friend the link or read out the 4-character room code (letters and digits). They open it on a phone or laptop, enter a name, and you’re on — no account, no app, just the browser. If your connection drops, reopen the page and you’re back in your seat mid-game.
- Exactly two players per room — it’s a true 2 player game, with no spectators.
- Nobody free right now? The room host can add a bot from the lobby and play solo.
- When the series ends, the host hits Rematch: scores reset, same room. The host can also end a match early — the leader wins.
- Every match counts toward your Elo rating (everyone starts at 1000) and the leaderboard. Games against the bot count too, but move your rating less than beating a human.
- Got a bigger group? Run a tournament — a bracket for 3–8 players where each pairing plays its own duel.
Only have five minutes? See our list of quick games for a break.
Bigger boards and other variants
Plenty of people know 4×4 tic-tac-toe, or the five-in-a-row game on an open grid called gomoku. Our room plays only the classic 3×3, three in a row — that’s what keeps each game to 20–40 seconds and the series moving. For a longer duel, try checkers or Battleship.
Strategy: why it’s a draw, and how to win anyway
There are 255,168 possible games of tic-tac-toe, but once you account for rotations and reflections there are only three opening moves: center, corner and edge. Computers solved them all long ago — perfect play is always a draw. So every win comes from a mistake, and your job is to invite one.
- Open in a corner. Against a corner opening, O has exactly one safe reply: the center. Any other square loses if you follow up correctly.
- Build a fork. Place a mark that threatens two lines at once. Your opponent can only block one.
- The opposite-corner trap. X takes a corner, O takes the center, X takes the opposite corner. If O now grabs another corner, X forks and wins. The only safe reply is an edge square.
- As O against a center opening, take a corner. Answering on an edge hands X a forced win.
- Use the restart rule. After you lose a game you start the next one as X — the perfect time for a corner opening and a trap.
The bot calculates every line to the end, but roughly one move in seven it plays a random square. Hold the draw, deny it forks, and pounce on the slip — that’s how you take a series off it.