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Infinite tic tac toe: rules, strategy and the winning move

By TicTacToe.net · Updated 15 October 2026 · 5 min read

In infinite tic tac toe your pieces don't stay put: you can only keep three, and the oldest one vanishes when you place a fourth. Ordinary tic tac toe is a guaranteed draw. This version isn't — we solved it by computer, and the first player can always win. The catch is the opening: it's the one square classic strategy tells you to avoid.

How to play

1. Play on a normal 3×3 grid. X goes first and players alternate, as usual.
2. Each player may have at most three marks on the board.
3. Once you have three, placing a new mark makes your oldest mark disappear first. You can't place on the square of a mark that's about to vanish.
4. Get three in a row and you win. Because the board never fills up, there's no draw by a full board.

You'll also see it called disappearing tic tac toe or tic tac toe where pieces disappear. Some apps tweak the rules — counting the limit for the whole board, or removing the old mark at a different moment — and that changes the strategy. Everything on this page is for the rules above, which is exactly how Fade mode on our 3×3 board works — you can play infinite tic tac toe online right here.

We solved it: the first player wins

Infinite tic tac toe has 116,074 possible positions (counting who is to move and the order each player's marks were placed, since that decides which one vanishes next). That's small enough to solve completely. We worked backwards from every finished game — a technique called retrograde analysis — until every position was marked as a forced win, a forced loss, or neither.

The results:

• From the empty board, X can force a win in 13 moves — X's 7th mark completes the line — however O defends.
• The only first moves that win are the four edges: B1, A2, C2 or B3.
• After a corner opening, O survives only by taking the centre. After a centre opening, O survives only by taking a corner. From there, neither side can force a win.
• In 68% of all positions, the player to move can force a win; in 21% they're lost whatever they do. Only 11% are genuinely balanced.
• No forced win anywhere in the game takes more than 17 moves.

We checked these results a second way, using the same game engine that runs our site, and both methods agree. The checks run automatically every time we update the site.

Why the edge works here

In classic tic tac toe the corners and centre are strong because they sit on the most lines, and marks are permanent. In the infinite version, permanence is gone: every mark you place is one you'll lose three moves later. The computer only tells us that the edge wins, not why — but here's our best reading. What matters is tempo: making threats that force your opponent's replies, so you control which of their marks disappear and when. An edge opening seems to keep X's options flexible enough to keep threatening, while O's own oldest marks fade out from under its defence.

Strategy tips

1. Watch both ghosts. Your oldest mark (shown faded in our game) leaves when you move; your opponent's leaves when they move. A two-in-a-row that includes a fading mark isn't a real threat.
2. Count threats after the fade. When you block, ask what your move costs you: the mark that disappears may have been blocking one of your opponent's lines.
3. Force, then strike. A threat your opponent must answer lets you predict their next move — and which of their marks disappears next. Chain two of those and the board opens up.
4. As O, take the right first reply. Centre against a corner, a corner against the centre. Against an edge, perfect play loses — so make X find the win.

Fade mode works on our bigger boards too: 4×4 and 5×5 keep five marks each and need four in a row, and 6×6 keeps six. Those are far too large to solve this way, so they're still a real fight.

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