Ultimate tic-tac-toe looks like nine games of tic-tac-toe at once, but it plays like one big game that rewards planning. The secret is the send rule: every square you choose decides where your opponent must play next. This tutorial explains the handful of ideas that turn random moves into a plan, shows the two most common mistakes in diagrams, and ends with a short practice plan you can follow against the computer on this site.
If you are still learning the rules, read the ultimate tic-tac-toe rules first. Everything here uses the rules this site plays: won boards are closed, a drawn board counts for nobody, and a move that points at a finished board gives a free move.
What you will learn
- Why every move is really two decisions.
- How to avoid sending your opponent to a board they can win.
- Why free moves are a gift, and how to stop giving them away.
- Why the center board deserves extra attention.
- When giving up a small board is the right choice.
- How to practise against the Easy, Medium and Hard computer.
Ultimate Tic-Tac-Toe Strategy: How to Win
Every move is two decisions
In ordinary tic-tac-toe you only ask one question: is this square good for me? In ultimate tic-tac-toe you must also ask: where does this square send my opponent? A square that sets up two in a row for you is worthless if it sends the other player to a board where they win at once.
Make it a habit. Before each move, look at the squares you are allowed to play, and for each one glance at the matching board on the big grid. Strike out every square that points to a board where your opponent has two in a row with the third square empty. Then choose the best of what is left.
Don’t send your opponent to a board they can win
This is the most common beginner mistake and the easiest one to fix. In the position below, X must play in the center board. O has two marks on the diagonal of the bottom left board, so the bottom left square of the center board would send O straight to the board O can win.
Any other empty square in the center board is safer. Sometimes all of your squares point to dangerous boards; then pick the board where your opponent’s win hurts you least, usually one that is not part of a line they are building on the big board.
Free moves are a gift
A move that points at a board that is already won or full gives your opponent a free move: they may play in any open board. That is like letting them choose the most dangerous spot on the whole board for themselves.
As the game goes on, more boards finish and free moves get harder to avoid. Keep a mental list of the finished boards, and treat the matching squares in every small board as squares you only play when you have to. On this site the outline makes it easy to see when a move gave someone a free choice: every open board lights up at once.
Value the center board
The center board is part of four lines on the big grid: the middle row, the middle column and both diagonals. Corner boards are part of three lines and edge boards only two, just like the squares of an ordinary tic-tac-toe grid. Winning the center board does not win the game, but it makes many lines possible for you and blocks them for your opponent.
The same counting works inside each small board. The center square of a small board takes part in four lines of that board. Remember the cost, though: a center square always sends your opponent to the center board. Playing center squares too often means your opponent spends many turns in the board you most want to control.
Sacrifice small boards
Not every small board is worth fighting for. If a board sits on lines that are already blocked on the big grid, for example because a drawn board or one of your opponent’s boards is in the way, winning it changes little. Giving it away can be fine when the move that allows it sends your opponent somewhere harmless, or keeps them away from the boards that decide the game.
A useful trick is to “park” your opponent. Win or fill a board you don’t care about with their help, while every send points them back into boards where they can’t do damage. Meanwhile, you build two in a row on the big grid with the boards that matter.
Make two threats on the big board
The winning idea from ordinary tic-tac-toe works here too, one level up. If you hold two boards in a line and also two boards in another line, your opponent can’t defend both third boards at once. Combine this with careful sends: when your opponent is forced to block in one board, make sure their blocking square sends you to the board you need.
Your first game, step by step
- Open in the center. As X, play the center square of the center board. O must answer in the center board too.
- Read the send before you move. For each square you could play, name the board it sends your opponent to, and check that board for two in a row.
- Answer threats inside boards. When you are sent to a board where your opponent has two in a row, block it unless you can win something bigger yourself.
- Avoid finished boards. As soon as a board is won or full, treat the matching squares as squares you only play when nothing else is safe.
- Count lines on the big board. After every small board is won, look at the big grid as an ordinary tic-tac-toe position. Which lines are still open for each player?
- Go for the double threat. Aim for two lines of boards that need different third boards, then use your sends to keep your opponent away from both.
More strategy tips
- Two in a row is a promise, not a win. It only matters if your opponent is ever sent to that board while the third square is empty, or if you get there first.
- Think about the next send too. After your opponent replies, they will send you somewhere. Squares that point you back to a board you like are strong.
- Don’t chase every small board. Winning five scattered boards loses to three in a line.
- Use drawn boards as walls. A drawn board blocks every line through it, for both players. Steer the game so that draws land on your opponent’s best lines.
Common beginner mistakes
- Playing the best-looking square in the current board without checking where it sends.
- Giving free moves late in the game, when many boards are finished.
- Fighting hard for a board that sits on no useful line.
- Forgetting that a center square always sends the opponent to the center board.
- Counting won boards instead of looking for lines of three.
A practice plan
Start against Easy. It plays mostly at random, but it always takes a small board that is there for the taking, so it quickly punishes careless sends. Your goal is to win without ever sending it to a board it can win. Then move to Medium, which plays out many quick practice games before each move and spots more of your mistakes. Finally try Hard, which thinks for longer. Play both as X and as O; moving first is an advantage, so a draw as O against Hard is a good result.
Use Undo freely while you learn. When the computer wins a board, undo your last move and ask where your send went wrong.
Play it now
Try these ideas in a game of ultimate tic-tac-toe with a friend on one device or against the computer. The board you must play in is always outlined, so you can focus on strategy. To brush up on the basics of the one-board game, see how to win at tic-tac-toe.