Tic-Tac-Toe Strategy: How to Never Lose and Win More Often
Tic-tac-toe looks like a children's game, and it is, but it is also a perfect little strategy puzzle. With correct play from both sides, every game ends in a draw. That means one thing: if you lose at tic-tac-toe, you made a mistake, and if your opponent makes one, you can punish it. This guide shows you how to win tic-tac-toe, or at least never lose, using a few simple rules.
Practise each idea in our free online tic-tac-toe game, against an easy computer, an unbeatable one, or a friend on the same device.
Tic-tac-toe rules
Two players take turns placing their mark, X or O, in an empty square of a 3×3 grid. X usually moves first. The first player to get three marks in a row, horizontally, vertically or diagonally, wins. If all nine squares are filled and nobody has a line, the game is a draw.
Why the centre and corners matter
Lines through each square
There are eight possible winning lines: three rows, three columns and two diagonals. The centre square is part of four of them, every corner is part of three, and every edge square is part of only two. More lines mean more ways to win and more ways to block, which is why strong players open in the centre or a corner.
The fork: how games are really won
X now threatens two squares
You will rarely win by building a single line, because a careful opponent simply blocks it. Games are won with a fork: one move that creates two winning threats at the same time. Your opponent can block only one, so you complete the other. Every winning plan in tic-tac-toe is a plan to set up a fork.
How to play as X (first)
- Open in a corner. It is the opening that gives your opponent the most chances to go wrong. If O answers anywhere except the centre, you can force a win with correct play.
- If O takes the centre, take the opposite corner. A careless O who then plays another corner falls into the trap shown below.
- Opening in the centre is also safe: O must answer in a corner. If O answers on an edge, you can force a win.
- Avoid opening on an edge. It is not a losing move, but it gives O the easiest path to a draw.
How to play as O (second)
| If X opens in… | Your safe reply | Replies that lose |
|---|---|---|
| A corner | The centre | Any edge or corner |
| The centre | Any corner | Any edge |
| An edge | The centre, a corner next to X, or the opposite edge | The far corners and the neighbouring edges |
The opposite-corner trap
O must answer on an edge
A corner here loses
The most common way O loses: X takes a corner, O correctly takes the centre, X takes the opposite corner, and then O plays a corner. X blocks, and that block creates a fork. When you are O in this position, always answer on an edge.
Five mistakes that lose games
- Missing your own winning move because you were busy blocking.
- Missing your opponent's two-in-a-row.
- Answering a corner opening anywhere but the centre.
- Taking a corner in the opposite-corner trap.
- Playing the first square you see instead of checking all eight lines.
Playing the modes on PlayNovarc
Our tic-tac-toe game has four modes. Easy AI leaves openings, perfect for practising forks. Unbeatable plays perfectly, so your goal is to keep drawing; one loss ends the run. Infinite keeps only each player's last three marks on the board: when you place a fourth, your oldest mark disappears, so you must always watch which mark will vanish next. 2 Players lets you play X and O with a friend on one screen.
A tiny game with a big history
Three-in-a-row games have been played for thousands of years. Tic-tac-toe also has a place in computing history: in 1952, Sandy Douglas wrote OXO, a tic-tac-toe program for the EDSAC computer at the University of Cambridge, often counted among the first video games ever made. Counting every move order, there are 255,168 possible games, yet with best play every one of them ends in a draw.
Frequently asked questions
Can you always win at tic-tac-toe?
No. Against a perfect opponent the best result for either player is a draw. You can, however, always avoid losing, and you can win whenever your opponent makes a mistake.
What is the best first move in tic-tac-toe?
A corner. It is as safe as the centre and gives your opponent more ways to go wrong.
Is it better to go first or second?
First. Going first gives you the initiative and more chances to set up a fork.
Can you beat the Unbeatable mode?
No, it plays perfectly. The challenge is to keep drawing as many rounds in a row as you can.
Play a few rounds now
Open tic-tac-toe on PlayNovarc, start against Easy AI and win with a fork, then switch to Unbeatable and try to hold ten draws in a row. Ready for a bigger board? Try Connect Four, Dots and Boxes, or the full strategy of chess with our guide to the Opera Game. You can also browse all board games.
