Tic tac toe has a reputation as a kids' game, and there's a reason: between two players who know what they're doing, every single game ends in a draw. But that little word — know — is doing a lot of work. Most people don't actually know the strategy. They know fragments of it. Which means that if you learn the whole thing, you will quietly win far more often than you should. Here's the complete picture.
The opening move: center, corner, or edge?
There are only three genuinely different first moves in tic tac toe — the center, a corner, or an edge. Everything else is a rotation or mirror of one of those.
- The center is the strongest square by the numbers. It sits on four winning lines (one row, one column, two diagonals) — more than any other square. If your opponent replies with anything other than a corner, you can force a win.
- A corner is the trickiest opening in practice. It sits on three lines, and it invites mistakes: if your opponent replies with anything other than the center, you can usually force a win with a fork. Many experienced players open with a corner precisely because the punishing replies are less obvious.
- An edge (a middle square on a side) is the weakest opening — only two lines pass through it. It's not losing, but it gives you nothing.
Forks: the only real weapon
You will almost never beat a decent player by completing a simple line — they'll see the threat and block it. Every real tic tac toe win comes from a fork: a position where you threaten two lines at once, so your opponent can only block one.
The classic example: you have marks in two corners on the same side of the board with the space between them empty, plus another developing line. Your opponent blocks one threat, you complete the other. Building a fork usually takes three moves of quiet setup — the trick is making each move look like it's doing something else.
How to never lose as the second player
Going second is harder — you're reacting — but a draw is always available if you follow three rules in priority order:
- If they opened in the center, take a corner. Any corner. Taking an edge against a center opening is the single most common losing mistake in tic tac toe.
- If they opened in a corner, take the center. Nothing else is safe long-term.
- Watch for the double-corner trap. If your opponent ends up with two opposite corners and you hold the center, do not take a third corner — play an edge. Taking the corner hands them a fork.
After the opening, the algorithm is simple: win if you can, block if you must, create a fork if possible, block their fork otherwise, then prefer center > corner > edge.
Bigger boards change everything
On RivalPit you can play tic tac toe from the classic 3×3 all the way up to 10×10, with a winning line of 3, 4, or 5. Once the board is bigger than the winning line, the game stops being a solved draw and starts behaving like Gomoku: the key skill becomes building open-ended rows — lines of your marks with empty space on both ends. An open-ended row of one-less-than-the-target is two threats in one, and just like a 3×3 fork, it can't be fully blocked.
Two habits carry over from the small board: central squares still touch the most lines, so claim space near the middle early, and it is almost always right to block an opponent's developing row one move before it becomes unstoppable rather than one move after.
The "most lines" variant
RivalPit also offers a scoring variant where the board fills up completely and every completed line counts as a point. Strategy shifts from knockout to efficiency: squares that participate in many potential lines are worth more, and a move that completes one line while setting up two more beats a move that completes one line, full stop. Corners and center dominate; edges are for tidying up.
Put it into practice
Reading strategy is one thing — having it ready at move three is another. Play a few rounds against the computer to drill the opening replies, then try the bigger boards against a friend and watch how differently the game feels.