Tic tac toe rules

Live board on this page — same controls as the home grid.

Vs computerTurn X
You (X) 0Draws 0AI (O) 0

Your turn (X) — tap a cell.

On this page

Tic tac toe rules

Short rules list for people who searched tic tac toe rules and want a checklist, not a story:

1. Board is 3×3. 2. X goes first; players alternate. 3. On a turn, place your mark in an empty cell. 4. Three in a row — row, column, or diagonal — wins. 5. Board full, no three → draw (cat’s game).

The board above follows these rules. For a gentler “first game” walkthrough, use how to play.

When

When to use

Quick rules lookup; settling an argument about diagonals; teaching someone who only needs five bullets.

When not

When not to

You want step-by-step first game coaching → how to play. You want strategy → strategy. You want Ultimate’s extra rules → ultimate.

Defaults

Assumptions

Classic 3×3 only on this URL. House variants (bigger boards, ultimate) have their own pages. Marks never overwrite a filled cell.

Steps

How

  1. Skim the five bullets in the intro.
  2. Tap a cell on the live board to feel a turn.
  3. Play to a win or draw once.
  4. Jump to how to win when rules feel obvious.

Worked notes

Examples

  • Diagonal of three X → counts as a win — people forget diagonals under pressure
  • Nine cells filled, no three-in-a-row → draw; rematch with New game

Watch-outs

Gotchas

  • This page is shorter than how to play on purpose — checklist vs coaching.
  • Ultimate / 4×4 / 5×5 add rules; do not paste classic rules onto those boards.
  • “Rules” spam sites often have no board; ours stays playable.

Nearby pages

Compare

First-game coaching: how to playStrategy: strategyJust play: play

Also on this site

Related

Controls

Quick controls

  • New game — clear the board for a rematch.
  • Hint — a cell and a short reason (not a cheat promise).
  • Undo — step back a move while you practice.
  • Vs computer / 2 players — mode pages lock the matching controls.

FAQ

Common questions

Do diagonals count as a win?
Yes — either diagonal, plus any full row or column. Under time pressure people forget one diagonal; the engine does not.
Who goes first, and can marks overwrite each other?
X starts on a fresh classic board. You only place in empty cells; a filled cell stays filled until New game. No stacking, no capturing.
What is a cat’s game?
Old nickname for a draw: every cell filled, nobody has three in a row. Hit New game for a rematch; the rules do not award a winner by “more marks.”
Is noughts and crosses a different rulebook?
Same game under a UK name (noughts = O). Our US pages say tic-tac-toe; the three-in-a-row rule does not change.
Why is this shorter than how to play?
This URL is the checklist for people who only needed bullets. How to play walks a first game with more coaching. Ultimate / bigger boards add rules — do not paste this list onto those pages.