How to play
Players take turns placing their mark – X always goes first – on an empty square. On the classic board, the first to line up three marks in a row, column or diagonal wins. If the board fills up first, the game is a draw.
Four boards, four different games
| Board | To win | What makes it different |
|---|---|---|
| Classic 3×3 | Three in a row | Solved: perfect play always ends in a draw. |
| 5×5 | Four in a row | A bigger board with room to set up double threats. |
| Ultimate | Three small boards in a row | Every move sends your opponent to a specific small board. |
| Misère 4×4 | Avoid three in a row | Whoever completes three in a row loses. |
Three tips for the classic board
- Take the center or a corner first. They sit on more winning lines than the edge squares.
- Block before you build. If your opponent has two in a row with the third square empty, take it.
- Look for a fork. A move that creates two threats at once cannot be blocked in one turn.
With friends, by code
Want to play someone on another phone? Press Open a room, then send the five-digit code or the link. Your friend types the code (or just opens the link), and once you are both in, the host presses Start the game. The board you pick before opening the room is the board you both play. After each game you can ask for a rematch, and the first move switches sides each time.
You do not need an account. Instead of a chat there are quick phrases and emoji, so the room stays friendly for players of every age. If your connection drops, the game waits for you: reopen the page and you go straight back to your seat.
To be honest about the limits: the room only passes moves between the two phones, and each phone checks every move against the rules. Nobody referees the players themselves, so a tampered phone could, for example, resign on your behalf or claim a win when you are away. That is why rooms are meant for playing with people you know. This part needs internet; everything else on this page works offline.
The computer levels
Easy looks one move ahead and sometimes plays at random. Medium looks a few moves ahead and rarely blunders. Hard plays the 3×3 and misère boards perfectly – it has worked out every position – and searches deeply on the larger boards. Against the computer you switch between X and O after each game, so both of you get to start.
Frequently asked questions
Can you always win tic-tac-toe?
No. On the classic 3×3 board, two players who make no mistakes always draw. Our Hard computer plays perfectly on 3×3, so the best you can do against it is a draw – unless you find a board where it can be beaten.
What is ultimate tic-tac-toe?
Nine small boards inside one big board. The square you play in decides which small board your opponent must play in next. Win a small board with three in a row, and win the game with three small boards in a row.
What is misère tic-tac-toe?
The reverse game: on a 4×4 board, whoever makes three in a row loses. It turns every instinct upside down.
Does it work without internet?
Yes. Against the computer or with two players on one device, the game works fully offline – on a plane, too. Only playing with a friend on another phone needs internet.
How do I play tic-tac-toe with a friend online?
Open a room, send your friend the five-digit code or the link, and start the game when you are both in. No account is needed, and each of you plays on your own phone.