Plain 3×3 tic-tac-toe is a solved game. If both players play well, it always ends in a draw, which is why most people stop playing it around the age of eight.
Ultimate Tic Tac Toe takes that 3×3 board and nests nine of them inside a larger 3×3 grid. It adds exactly one rule — the square you play in decides which board your opponent must play in next — and that single line turns a drawn game into a genuine contest of position.
This article sets out the rules precisely and then covers the five things a new player should learn first.
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The rules of Ultimate Tic Tac Toe
Three rules: your square chooses their board, three in a row wins a small board, and three small boards in a row wins the game.
There are nine 3×3 grids arranged themselves in a 3×3 pattern. The small grids are called local boards and the overall arrangement is the global board.
▼The three rules
① The position of the square you play sends your opponent to the matching local board. Play in the top-right square of any local board and your opponent must play in the top-right local board
② Three in a row within a local board wins that board
③ Three won local boards in a row on the global board wins the game
That is everything. Rule one, though, always comes with an exception attached.
The exception: a finished board means a free move
If the local board you are sent to has already been won or is completely full, you may instead play anywhere on the entire grid. This is called a free move.
This exception drives nearly all of the strategy. The difference between a beginner and an experienced player shows up here more than anywhere else.
When every board is finished
If all nine local boards resolve without anyone getting three in a row on the global board, the game is a draw. Some rule sets instead award the win to whoever captured more local boards. In the app described below this is a toggle, off by default.
Why it beats ordinary tic-tac-toe
Because the question changes from “where do I want to play” to “where do I want to send my opponent.”
In plain tic-tac-toe, choosing a move means finding the square that helps you. There are at most nine options and a handful of memorised lines cover them all.
In Ultimate Tic Tac Toe, every move carries two meanings at once.
▼The two halves of every move
▶ Local value: does it build your three in a row, or block theirs?
▶ Sending value: which local board does it hand your opponent?
These two usually conflict. The strongest square locally often sends your opponent somewhere excellent for them. Choosing the right destination often means making a poor move on the board in front of you. That tension appears on every single turn.
Plain tic-tac-toe draws because the board is small enough to calculate completely. Ultimate Tic Tac Toe is nine times larger and requires reading chains of forced destinations, which puts it beyond calculation for a human. That is why games are decided.
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Strategy 1: never hand over a free move
Sending your opponent to a finished board is almost always a mistake. It gives them the run of all nine local boards.
A player with a free move picks the single best move available anywhere on the grid. That is close to giving them a free turn.
Beginners fall into this constantly, because they are concentrating on completing a line in the board in front of them. Before playing, check whether the local board matching your square is still alive. This habit alone changes results.
The reverse is also true: when you receive a free move, spend it well. Do not play the first reasonable square. Pick the one that lets your next move drop your opponent somewhere awkward.
Sometimes you should leave a board unfinished
A more advanced idea: deliberately decline to win a local board.
Once you capture a board, that board becomes a place that grants your opponent a free move whenever you send them there. The more boards get resolved, the narrower your own choice of destinations becomes. Capturing boards is not automatically good.
Strategy 2: the centre board is worth the most
The centre local board sits on four of the eight winning lines. It is the most valuable of the nine.
The global board has eight winning lines: three rows, three columns and two diagonals. Counting how many lines each position touches makes the hierarchy obvious.
| Position | Lines through it | Value |
|---|---|---|
| Centre (1 board) | 4 | Highest |
| Corners (4 boards) | 3 | High |
| Edges (4 boards) | 2 | Low |
The same hierarchy applies inside each local board. The centre square of a local board sits on four of that board’s lines.
Now combine that with the sending rule. Playing the centre square of a local board sends your opponent to the centre local board. So taking the strongest square locally and handing over the most valuable board are the same action, always.
How you resolve that trade-off, position by position, is the core skill of the game.
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Strategy 3: recognise the send-back loop
If your opponent answers in the square matching the board they were sent to, you get sent straight back where you came from.
Say you play the top-left square of the centre board. Your opponent is sent to the top-left board. If they then play the centre square of the top-left board, you are sent back to the centre board.
Loops like this can be built deliberately. Construct a shuttle that benefits you and keeps your opponent away from the boards they want, and they simply cannot get where they need to go.
▼Building a loop
▶ Build the shuttle around a board where you already have two in a row
▶ Never send them to a board where they have two in a row
▶ Use the turns the loop buys you to improve your global position
Strategy 4: decide which boards to give up
You do not need all nine. Three in a row wins, so the other six are terrain for controlling where your opponent goes.
Winning the game requires exactly three local boards. The remaining six are, bluntly, real estate for manipulating destinations.
When you judge early that a board is going to fall to your opponent, stop contesting it and start choosing squares in it purely for where they send your opponent. Making that switch gives you far more control over the flow of the game.
The test is simple: is this board on a line you are actually trying to win? Commit to taking three boards that form one line — centre and corners are the natural candidates — and the boards you can abandon become obvious.
Strategy 5: build a double threat on the global board
Create two global lines that each need one more board, and your opponent can only stop one.
The idea is the same as ordinary tic-tac-toe, but here it takes dozens of moves to set up, which makes it decisive when it lands.
Crucially, a global double threat is built by restricting where your opponent can move. Hold two boards that are each one capture from completing a line, and put your opponent in a position where they do not want to be sent to either. If they have no free move available, their destination is forced, and eventually they must be sent into one of them.
This is why strategy 1 matters so much. Keep handing your opponent free moves and this finish will never arrive.
Three ways beginners lose
▼Fix these and your results change
① Playing only for the local win: focused on three in a row, never checking the destination
② Capturing every board you can: each captured board shrinks your own set of usable destinations
③ Wasting free moves: spending a near-free turn on a small immediate gain
The first is by far the most common, and also the easiest to fix. Say out loud where your opponent will be sent before you commit to a move. Do that until it becomes automatic.
Playing it
Rules and strategy do not stick from reading. Ten games played while consciously tracking destinations will change how the board looks to you.
This blog publishes Ultimate Tic Tac Toe as an iOS app, Ultimate Tic Tac Toe (究極マルバツ). The board you are allowed to play in is always highlighted, so the rules come naturally even before you have memorised them.
▼What it includes
▶ CPU opponents at easy, normal and hard, plus a hidden fourth level unlocked by winning three in a row against hard
▶ Pass and play on a single device
▶ Online matches with automatic matchmaking, falling back to a CPU game if no opponent appears
▶ Classic mode with the ordinary 3×3 game
▶ Hints and takebacks, so you can test ideas mid-game
CPU games, pass and play, and classic mode all work offline; only online matches need a connection. The app is free to play with ads, and requires iOS 15.0 or later.
The takeback feature is what makes it useful for practice. When you realise you sent your opponent somewhere terrible, roll back and try the alternative. That loop teaches the game faster than anything else.
Related reading
▶ Seven sudoku techniques and the order to learn them — another deceptively simple paper game
▶ Building a 3D dice game with Three.js and Ammo.js — how another game on this site was built
Summary
Ultimate Tic Tac Toe has three rules, but the single line “the square you play decides your opponent’s next board” is what turns a drawn game into a real one.
Winning comes down to judging every move on two axes at once: its value on the local board, and where it sends your opponent. Those two rarely agree, so every turn is a decision.
In order: never hand over a free move, respect the centre board, build send-back loops, use lost boards as terrain, and finish with a global double threat.
Start with just one of them — check where your opponent goes before you play. Add the rest once that is automatic.
