The Basics
Tic tac toe is a two-player game played on a 3×3 grid of nine squares. One player is X, the other is O. X always moves first.
The Three Rules
- Players take turns placing their mark in any empty square.
- The first player to get three of their marks in a row - Horizontally, vertically or diagonally - Wins.
- If all nine squares are filled and nobody has three in a row, the game is a draw (also called a "cat's game").
The Eight Winning Lines
There are exactly eight ways to win on the classic board.
Rows, Columns and Diagonals
| Type | Count | Lines |
|---|---|---|
| Rows | 3 | Top, middle and bottom row |
| Columns | 3 | Left, center and right column |
| Diagonals | 2 | Top-left to bottom-right, top-right to bottom-left |
See It in Action
Here's a finished game - X wins with the top row:
Rules Worth Knowing
Turns and Marks
- X moves first. This is a real advantage, so alternate who plays X between rounds (our 2 player mode does this automatically).
- Marks are permanent. Once placed, a mark can't be moved or removed.
How the Game Ends
- The game ends immediately when a player completes a line. The remaining squares stay empty.
- Two lines can never finish at once. The game stops the second one line is complete, before the other player gets a turn to build a second line.
5×5 Variant: Four in a Row
Our 5×5 mode keeps the same turn structure but changes two things.
What Changes on the Bigger Board
- The board is 5×5 (25 squares) instead of 3×3.
- You need four in a row to win, not three - Again in any row, column or diagonal. A diagonal line of four can start anywhere it fits, not just the corners.
Why Three in a Row Isn't Enough
Three in a row does not win on the 5×5 board. But three marks with both ends open usually forces a win one move later. That's where the real strategy lives.
What Counts as a Draw?
Why Draws Are Normal, Not a Mistake
If all nine squares fill up and no line of three exists, the game is a draw. It's traditionally called a "cat's game" (the cat gets it, because nobody else does). A draw isn't something gone wrong. Between two players who both know the game well, it's the normal result.
Tic tac toe is a solved game. That means mathematicians have worked out every possible way it can be played. With perfect play (nobody making a mistake) from both sides, every single game ends in a draw. So any game that ends with a winner happened because someone slipped up.
Scoring Draws Over a Match
Playing more than one game? Here's a useful convention: draws score zero points, and the players swap who goes first (or the loser of the last game starts next). Our 2 player mode handles both automatically.
Common Rules Questions, Settled
Can you win with a diagonal?
Yes. Both diagonals always count. This is the rule kids most often skip by mistake, and they shouldn't: the two diagonals both pass through the center square, so they sit behind many of the quickest wins.
Can both players win at once?
No. The game stops the instant one line is complete. Each turn adds only one mark, so there's never a moment where a second line could finish for the other player too.
Do you have to take a winning move?
No rule forces you to. But there's never a good reason not to. Waiting never makes a winning move any better.
Can you skip a turn?
No. You must move every turn, even if every open square seems to help your opponent. Running out of safe squares is a real way to lose - It's the entire idea behind misère tic tac toe.
Is there a standard board notation?
Yes. Squares are usually numbered 1 through 9, left to right, top to bottom. That makes it easy to play by voice or write a game down.
More questions? Our FAQ page covers everything from "who invented tic tac toe" to "can the computer be beaten".
Rules of the Popular Variants
At a Glance
| Variant | Board | Win condition |
|---|---|---|
| 4×4 | 4×4 | Four in a row |
| 5×5 | 5×5 | Four in a row |
| Ultimate | Nine 3×3 boards | Win three small boards in a row; your square choice sends your opponent to that board |
| Misère | 3×3 | Reversed - Three in a row loses |
| Wild | 3×3 | Either player may place X or O; any three-in-a-row wins for the mover |
Which Variant to Try Next
New to variants? Start with 4×4 - It's the smallest step up from the classic board. Ready for something bigger? Ultimate tic tac toe turns nine boards into one giant strategy puzzle. Want to feel clever? Misère flips the win condition upside down.
How Long Does a Game Take?
Nine Moves, Sixty Seconds
A classic game lasts at most nine moves. Most games wrap up in 20 to 60 seconds.
Why the Game Has Lasted for Centuries
That short playtime is the whole charm. It's the perfect game for a quick break. It's also why the game has survived from Roman terni lapilli boards scratched in stone to the phone in your pocket.
Ready to play? Start a game against the computer, or jump straight to the strategy guide to learn how to stop losing. Teaching someone? Print a few blank boards and use the kids method.