How do you play ultimate tic-tac-toe?

The big board is a 3 by 3 grid of small tic-tac-toe boards. Players take turns placing X or O in one cell of a small board, and the position of that cell inside its small board picks the small board the opponent must play in next: take the top-right cell of any board and your opponent must play in the top-right board. The first move can go anywhere. Win a small board with three in a row as usual, and win the game with three small boards in a row. Here boards and cells are both numbered 1 to 9 from the top left, so a move written 5.1 is the top-left cell of the centre board.

What happens if you are sent to a board that is already won or full?

You may play in any small board that is still unfinished. The tool shows this in the side pane, for example O to board 5, already won by X, so O may play in any open board, and every open board lights up. A small board that has been won or filled takes no more moves, so a try in one is refused with the reason.

Can you keep playing in a small board after it has been won?

Not here. Some groups play on in won boards, but this tool follows the common rule that a won board is closed: its empty cells stay empty, it shows the winner's mark across it, and being sent there lets you choose any unfinished board instead.

How do you win ultimate tic-tac-toe, and can it end in a draw?

Win three small boards in a line, across, down or diagonally, and the game ends at once. A small board that fills up with no three in a row counts for nobody and blocks any line through it. If every small board is won or full and neither side has three in a line, the game is a draw. There is no tiebreak by counting boards.

Can I play ultimate tic-tac-toe against the computer?

Yes, choose Computer. The side that starts plays X, so you choose You start or Computer starts. The computer is a beginner: it searches at most three moves ahead (its move, your reply and its next move) for up to 750 ms in a background worker, scores positions by small boards won, two-in-a-rows and won boards lined up on the big board, and picks at random among moves it scores almost the same. It takes a win when it sees one, but it is not perfect play. If the background search cannot run in your browser, the computer plays a quick rule-based legal move instead and says so.

Can two people play on one device?

Yes, choose Two players and take turns on the same screen, with X or O starting as you pick. There is no online play and no account. Changing the mode or who starts in the middle of a game asks first, because it begins a new game.

Can I undo a move or save a game?

Undo takes back the last move with two players. Against the computer it takes back your move and the computer's reply, so it is your turn again. The game in progress is kept in this browser and comes back when you return, and Save position keeps up to six positions, each with its mode, whose turn it is and the board they must play in. Nothing is sent anywhere, and Start over at the top of the page forgets the game and the saved positions.

Can I play with a keyboard?

Yes. Tab to the board, then use the arrow keys to move between all 81 cells, Home and End to jump along a row, and Enter or Space to play. A cell you cannot play is still reachable, and pressing it says why the move is refused.

Ultimate Tic-Tac-Toe

Play ultimate tic-tac-toe, nine small tic-tac-toe boards inside one big one, against a beginner computer or with a friend taking turns on the same device. The cell you take decides which small board your opponent plays in next, so the board lights up the small board the next move must go in, the side pane says where the last move sends the other player and why, and a move that breaks the rules is refused with the reason. When you are sent to a small board that is already won or full, every unfinished board opens up instead. Win three small boards in a row, column or diagonal to win the game. You can play by mouse, touch or keyboard, and on a phone a move pad under the board repeats the small board you are playing in with larger buttons, asking first which board when any open one will do. Undo takes a move back, the game in progress is kept in this browser, and Save position keeps up to six positions to come back to.

board0 moves

Getting the board ready

Loading any game saved in this browser.

open: 81 cells in 9 boards
last move: none yet
sends: X may start in any board
history: none yet

Getting the board ready.

Saved in this browser

Mode

First move

To move

You (X), any board

Boards won

X 0, O 0

Getting the board ready.

First move in cell 5X opens in cell 5 of any board
O must play next in board 5
Sent to a won or full boardX 4.5 sends O to board 5, won by X
O may play in any of the 8 unfinished boards
Every small board decided, none three in a linewon or full, no line for either side
a draw; three won boards in a line wins at once

Saved positions

None yet. Save position keeps up to 6 positions in this browser, each with its mode, whose turn it is and the board they must play in.

Game as text

Ultimate tic-tac-toe, against the computer, you are X
You (X) to move, any board
Boards won: X 0, O 0

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Moves as board.cell, each numbered 1 to 9 from the top left:
none yet

Boards and cells are numbered 1 to 9 from the top left, so 5.1 is the top-left cell of the centre board. On the board, Arrow keys move between all 81 cells, Home and End jump along a row, and Enter or Space plays. On a phone, the move pad under the board plays the same moves with larger buttons.

Common questions

How do you play ultimate tic-tac-toe?: The big board is a 3 by 3 grid of small tic-tac-toe boards. Players take turns placing X or O in one cell of a small board, and the position of that cell inside its small board picks the small board the opponent must play in next: take the top-right cell of any board and your opponent must play in the top-right board. The first move can go anywhere. Win a small board with three in a row as usual, and win the game with three small boards in a row. Here boards and cells are both numbered 1 to 9 from the top left, so a move written 5.1 is the top-left cell of the centre board.
What happens if you are sent to a board that is already won or full?: You may play in any small board that is still unfinished. The tool shows this in the side pane, for example O to board 5, already won by X, so O may play in any open board, and every open board lights up. A small board that has been won or filled takes no more moves, so a try in one is refused with the reason.
Can you keep playing in a small board after it has been won?: Not here. Some groups play on in won boards, but this tool follows the common rule that a won board is closed: its empty cells stay empty, it shows the winner's mark across it, and being sent there lets you choose any unfinished board instead.
How do you win ultimate tic-tac-toe, and can it end in a draw?: Win three small boards in a line, across, down or diagonally, and the game ends at once. A small board that fills up with no three in a row counts for nobody and blocks any line through it. If every small board is won or full and neither side has three in a line, the game is a draw. There is no tiebreak by counting boards.
Can I play ultimate tic-tac-toe against the computer?: Yes, choose Computer. The side that starts plays X, so you choose You start or Computer starts. The computer is a beginner: it searches at most three moves ahead (its move, your reply and its next move) for up to 750 ms in a background worker, scores positions by small boards won, two-in-a-rows and won boards lined up on the big board, and picks at random among moves it scores almost the same. It takes a win when it sees one, but it is not perfect play. If the background search cannot run in your browser, the computer plays a quick rule-based legal move instead and says so.
Can two people play on one device?: Yes, choose Two players and take turns on the same screen, with X or O starting as you pick. There is no online play and no account. Changing the mode or who starts in the middle of a game asks first, because it begins a new game.
Can I undo a move or save a game?: Undo takes back the last move with two players. Against the computer it takes back your move and the computer's reply, so it is your turn again. The game in progress is kept in this browser and comes back when you return, and Save position keeps up to six positions, each with its mode, whose turn it is and the board they must play in. Nothing is sent anywhere, and Start over at the top of the page forgets the game and the saved positions.
Can I play with a keyboard?: Yes. Tab to the board, then use the arrow keys to move between all 81 cells, Home and End to jump along a row, and Enter or Space to play. A cell you cannot play is still reachable, and pressing it says why the move is refused.

Rules as played here: the cell you take chooses the small board your opponent plays in next, and if that board is already won or full they may play in any unfinished one. Three small boards won in a line wins the game, and a game where every small board is decided without such a line is a draw. The computer is a beginner that searches at most three moves ahead for up to 750 ms, not perfect play, and your game and saved positions stay in this browser only.