How to Play Tic Tac Toe

Tic Tac Toe is a two-player game on a 3×3 grid. One player uses X, the other uses O. The goal is to claim three cells in a straight line before the other person does.

Setup

Draw nine empty squares, or play Tic Tac Toe online and skip the paper. X usually starts. On Duetly, X is also the first seat in an online room — the person who creates the room.

A turn

On your turn you place your mark in one empty cell. You cannot overwrite a mark that is already there. After you place, it is the other player's turn. That is the entire move list.

How you win

You win by filling any row, column, or diagonal with your own mark. There are eight winning lines: three rows, three columns, and two diagonals.

1. Top row, middle row, or bottom row
2. Left column, middle column, or right column
3. Top-left to bottom-right diagonal
4. Top-right to bottom-left diagonal

A sample game

X takes the center. O takes a corner. X takes the opposite corner, building a diagonal threat. O must block that diagonal. X then takes a side cell that creates two threats at once — a fork. O can block only one. X wins on the next turn. That pattern is why the center and corners matter; the strategy guide walks through forks in detail.

Draws

If every cell is filled and nobody has three in a row, the game is a draw. Between two careful players, draws are common. That is not a failed game — it is the expected result of perfect play.