How to Win at Tic-Tac-Toe (and Never Lose)
Tic-tac-toe, also called noughts and crosses, looks too simple to have a strategy. In fact it has a complete one. With correct play neither side can force a win, so a careful player never loses, and a player who knows the traps wins often against anyone who does not.
This guide gives a turn-by-turn priority list, the strongest openings for the first player, the correct replies for the second player, and how forks decide almost every game. The positions were checked by computer search of every possible game. It ends with how to practise in this Tic-Tac-Toe game.
A priority list for every turn
On each move, go down this list and play the first one that applies:
- Win: if you have two in a line and the third square is empty, take it.
- Block: if your opponent has two in a line with the third square empty, take that square.
- Fork: make a move that creates two lines of two at once. Your opponent can only block one.
- Block a fork: if your opponent could fork next move, stop it, ideally by making a two-in-a-row of your own that forces them to block somewhere harmless.
- Centre: take the centre if it is free.
- Opposite corner: if your opponent has a corner and the opposite corner is free, take it.
- Any corner.
- Any edge.
Following steps 1 to 4 carefully is enough never to lose. Steps 5 to 8 are the tie-breakers that give your opponent the most chances to go wrong.
Going first: the corner opening
Both the centre and a corner are good first moves, and neither can lose. The corner is the better practical choice because the second player has only one safe reply: the centre. Every other reply, including the other corners and all four edges, can be beaten with correct play.
A typical win after a bad reply
Number the squares 1 to 9 from the top left, row by row. You play the top-left corner (1). Your opponent answers with the top edge (2). You take the centre (5), threatening 1-5-9, so they must block at 9. Now you take the bottom-left corner (7). That threatens both 1-4-7 and 3-5-7, a fork, and they can only stop one of them.
If they do take the centre after your corner opening, the game should be a draw. Play the opposite corner (9) and wait: if they then take a corner, block their line and look for a fork; if they take an edge, you will usually have to block, and the game ends level.
Going second: the safe replies
- Opponent takes a corner: take the centre. This is the only reply that does not lose.
- Opponent takes the centre: take a corner. Any edge reply loses against correct play.
- Opponent takes an edge: take the centre, one of the two corners next to their mark, or the edge opposite it. The other replies can lose.
After the first reply, the classic trap for the second player is the double corner. If the first player holds two opposite corners and you hold the centre, do not take a corner. Take an edge instead, which forces them to block and keeps you safe. Taking a corner here lets them fork.
Forks: how almost every game is won
A fork is a single move that creates two separate threats. Because your opponent has only one move, they can block one line but not both. In practice, nearly every win between players who block properly comes from a fork.
Forks usually come from corners, because each corner sits on three lines (a row, a column and a diagonal) while the four edges sit on only two. Two of your marks in corners, with the squares between them empty, are often one move away from a fork. Look for them on your own turn, and check for your opponent's before you move.
How to practise
Play a few rounds where you only open in the corner, then a few where you always reply in the centre. Say the priority list in your head before each move. Once blocking is automatic, start looking two moves ahead for forks. Swap who plays first each round so both of you practise both roles. For the numbers behind the game, see how many possible tic-tac-toe games there are.
Playing in this Tic-Tac-Toe game
Tic-Tac-Toe (○×) is made for two people sharing one device:
- Decide who plays ○; every new game starts with ○.
- Tap an empty square to place your mark. The line above the board shows whose turn it is.
- Pass the device. The game detects three in a row on any of the eight lines and announces the winner, or declares a draw when the board is full.
- Press Play Again to clear the board, and swap who takes ○ so you both practise going first.
There is no computer opponent and no score history, so keep a tally on paper if you want one. The game is also on iPhone and Android.
Frequently asked questions
Can you always win at tic-tac-toe?
No. Against a player who never makes a mistake, the best result for either side is a draw. You can win only when your opponent slips.
What is the best first move in tic-tac-toe?
A corner or the centre; both are safe. A corner gives the opponent only one non-losing reply, the centre, so it sets more traps.
How do you never lose at tic-tac-toe?
Always complete your own line if you can, always block your opponent's, and stop any move that would give them two threats at once.
What is a fork in tic-tac-toe?
A move that creates two lines of two at the same time. Your opponent can block only one, so the other wins.
Can I play against the computer in this game?
No. It is a two-player game on one screen.