How to Play Ultimate Tic Tac Toe

By Jaques of London · Est. 1795 · Updated 2026-08-17

Ultimate Tic Tac Toe takes the familiar noughts and crosses grid and nests it inside a larger version of itself, producing a game that is far richer than its components suggest. Every move has a double consequence: it claims a square in a small board and simultaneously dictates which small board your opponent must play in next, creating a constant tension between local and global strategy.

It is played with pen and paper on any flat surface and requires no equipment beyond a sheet of paper and two different writing implements. Because it is portable, cheap, and quick to learn but genuinely difficult to master, it is equally popular with children in classrooms and adults looking for a compact two-player challenge.

A little history

The origins of Ultimate Tic Tac Toe are unclear. Tic Tac Toe itself is one of the oldest recorded pen-and-paper games, with evidence of similar grid games dating to ancient Rome, but the nested, recursive variant now widely called Ultimate Tic Tac Toe appears to have spread through recreational mathematics communities and puzzle enthusiasts in the late twentieth and early twenty-first centuries. It gained significant mainstream visibility after being discussed on several popular mathematics and puzzle blogs in the 2010s, but no single inventor or first publication has been definitively established.

Setting up

1. Draw a large tic-tac-toe grid on the paper: three columns and three rows, producing nine cells.
2. Inside each of those nine cells, draw a smaller tic-tac-toe grid: again three columns and three rows.
3. You now have a 3x3 arrangement of nine small boards, each containing nine squares, for 81 playable squares in total.
4. Label or colour-code the nine small boards for reference if helpful: top-left, top-centre, top-right, middle-left, middle-centre, middle-right, bottom-left, bottom-centre, bottom-right.
5. Decide who plays noughts (O) and who plays crosses (X) and who goes first, by any agreed method such as a coin toss.

How to play

1. The first player may place their mark in any single square of any one of the nine small boards to start the game.
2. Look at the position of the square just claimed within its small board. The small board whose position on the large grid mirrors that square position is where your opponent must play their next mark. For example, if you played in the top-right square of any small board, your opponent must play their next mark somewhere inside the top-right small board.
3. Your opponent places their mark in any free square within the designated small board.
4. Again, the position of that square within its small board determines which small board you must use for your next turn.
5. Continue alternating turns in this way, always sending your opponent to the small board that corresponds to the position of the square you just played.
6. If you are sent to a small board that has already been won or that is completely full with no empty squares, you may play in any empty square on any small board that has not yet been won or filled. Both conditions (won and full) grant this freedom.
7. Win a small board by placing three of your marks in a row within it, horizontally, vertically, or diagonally, exactly as in standard tic-tac-toe.
8. Once a small board is won, mark it clearly with a large version of the winner's symbol. That board is closed; neither player may play further squares inside it.
9. A small board that is completely filled with no three-in-a-row for either player is a draw. Mark it as drawn. It counts as won by neither player for the purpose of the large board.
10. Continue until the large game is decided. See the Winning section for how the overall winner is determined.

Winning and scoring

A player wins the overall game by claiming three small boards in a row on the large 3x3 grid, horizontally, vertically, or diagonally, exactly as in standard tic-tac-toe. The first player to achieve this wins immediately and the game ends. If all nine small boards are decided (won or drawn) and no player has three in a row on the large grid, the game is a draw. Some players use a points tiebreak in that case: count the number of small boards each player has won and the player with more is the winner, with an equal count remaining a draw.

The fine points

The most common dispute concerns what happens when a player is sent to an already-decided board. The standard ruling, and the one most consistent with the spirit of the game, is that any small board that has been won or that contains no empty squares releases the incoming player to choose freely among all remaining open boards. It is important to agree this rule before play begins, as some informal players instead rule that only fully filled boards grant free choice, not won boards that still contain empty squares. The latter rule is a legitimate variant but changes strategy considerably.

A second frequent dispute arises over drawn small boards: do they count as blocked for both players or can they still be used as a destination? The standard answer is that once a small board is full it cannot receive any more marks, but a won board may still physically contain empty squares. Those squares are irrelevant once the board is won: no mark may be placed in a won board for any reason, and being directed there simply grants free choice. Agree this at the outset to avoid arguments mid-game.

How to win more often

• Think two moves ahead: every square you claim sends your opponent somewhere specific, so ask not only whether a move wins a small board but where it forces your opponent to go.
• Avoid completing a small board in a way that sends your opponent to a board where they can immediately win it, particularly if that winning move then sends you somewhere disadvantageous.
• The centre small board is the most valuable position on the large grid because it contributes to four possible winning lines (row, column, and both diagonals). Contest it early.
• If you have freedom to choose any board, prioritise sending your opponent to a small board you have already partially won, so they are forced to play defensively rather than advancing their own agenda.
• Do not focus entirely on small-board wins at the expense of the large grid. Winning a small board in a corner or edge that does not contribute to your three-in-a-row on the large grid may be strategically worthless or actively harmful if it sends your opponent somewhere useful.

Variations

No Free-Choice Rule

Under this stricter variant, a player sent to a won or full small board loses their turn entirely rather than gaining a free choice. This creates a stronger incentive to avoid filling small boards prematurely and makes late-game routing more punishing. It is a significant departure from the standard game and suits experienced players who want a sharper challenge.

Drawn Boards Count as Half a Point

Instead of treating drawn small boards as neutral, each drawn board awards half a point to each player at the end of the game when totalling small-board scores. This makes fighting for draws in contested small boards worthwhile and is useful when the game frequently ends without a three-in-a-row on the large grid.

Recursive Ultimate Tic Tac Toe

A further nesting of the concept: each cell of each small board is itself a tiny tic-tac-toe grid, producing a three-level structure. Play proceeds by the same send-your-opponent logic applied at every level simultaneously. This version is extremely complex, genuinely time-consuming, and best suited to players thoroughly comfortable with the standard two-level game.

Open Starting Rule

To reduce the first-player advantage that can arise from the standard free first move, the first player is restricted to playing only in the centre square of the centre small board on their opening turn, or alternatively only in any corner square of any corner small board. Both restrictions are in common informal use and either produces a more balanced early game.

Ultimate Tic Tac Toe: frequently asked questions