Tic Tac Toe

How do you play Tic Tac Toe?

Two players take turns placing their mark, X or O, in an empty square of a 3x3 grid. X always goes first. The first player to get three of their own marks in a row, across, up and down, or diagonally, wins. If all nine squares are filled and nobody has a line, the game is a draw, which people sometimes call a cat's game.

Our version adds a pop-in animation to every mark, a strike line through the winning row, a score for the session and a win streak, so a quick game feels lively. Pick your board and opponent on the start screen and tap Play.

Is Noughts and Crosses the same as Tic Tac Toe?

Yes. Noughts and crosses, tic-tac-toe, tick-tack-toe and Xs and Os are all names for the same game, with the same rules. Noughts and crosses is the usual name in the UK, Australia and much of the Commonwealth, tic-tac-toe is the usual name in the United States and Canada, and Xs and Os is used in Ireland. The nought is simply the letter O. Whichever name you search for, you have found the right game.

Can you always win or draw at Tic Tac Toe?

Nobody can force a win at tic-tac-toe, but a perfect player can never lose. The 3x3 game is solved: if both players play perfectly, every game ends in a draw. There are only 255,168 possible games and 5,478 different legal positions, so a computer can look at all of them in an instant.

That is exactly what Hard does on the 3x3 board. It searches the whole game tree, so it never makes a mistake, and the best result you can get against it is a draw. We checked this by trying every possible sequence of moves against it as both X and O. If you want to win, play Medium or Easy, or try one of the bigger boards.

What is the best Tic Tac Toe strategy?

Play the following rules in order, and you will not lose a 3x3 game. They are close to the ones the researchers Allen Newell and Herbert Simon wrote into an early tic-tac-toe program.

• Win: if you have two in a row with an empty third square, take it.
• Block: if your opponent has two in a row, take the third square yourself.
• Fork: make a move that creates two lines of two at once, so they can only block one.
• Block a fork: if your opponent could make a fork next turn, stop it, either by taking the fork square or by forcing them to respond to a threat.
• Centre: take the middle square if it is free.
• Opposite corner: if your opponent is in a corner, take the corner opposite.
• Empty corner: take any free corner.
• Empty side: take a free edge square last.

What is the best first move as X?

A corner. If X starts in a corner, O has eight possible replies and only one of them, the centre, avoids losing against perfect play. Starting in the centre is also safe, but then O must reply in a corner, and a beginner playing O often goes wrong by choosing an edge. Starting on an edge gives O the easiest game, so avoid it.

Against a human who knows the basics, a corner opening still wins a lot of games, because the other player has to find the one correct reply. Against Easy or Medium, try a corner and then look for a fork on your second move.

How should O play?

If X plays the centre, reply in a corner, never an edge. If X plays a corner, reply in the centre. If X plays an edge, take the centre, or a corner next to it. After that, follow the same list: win if you can, block if you must, and look for forks.

The O player rarely wins against a good opponent, so being happy with a draw is part of the strategy. The satisfying moment is when X makes a small slip and you suddenly have a fork of your own.

Can I play Tic Tac Toe against the computer?

Yes. Pick Vs computer, choose a board size and a level, and choose whether you play X first, O second or at random.

• Easy: plays loosely. It often misses a block and sometimes puts a mark almost anywhere. Good for young children.
• Medium: always sees an immediate win and an immediate block, but it does not see forks coming. You can outsmart it by creating two threats at once.
• Hard: on 3x3 it searches the whole game and never loses. On 4x4 and 5x5 it uses alpha-beta search with a transposition table and line-based scoring, thinking about a second per move in the background, which makes it a tough opponent on a bigger board.

How do I play Tic Tac Toe with two players on one screen?

Choose 2 players, pick a board and tap Play. Pass the phone or share the laptop. The name cards above the board show whose turn it is, and the starting player swaps each game. The scoreboard counts each side's wins and the draws for as long as you keep the game open, so you can play a best-of-five on the same screen.

How do I play Tic Tac Toe online with a friend?

Choose Online friend, enter a name and tap Create a room. You get a six-letter code and a link. Send the link on WhatsApp, copy it or use your phone's share sheet. When your friend opens it, they join your room and you press Start game. The host chooses the board size before creating the room.

The two browsers talk directly to each other when they can and use a relay when a network blocks that, so it works across different Wi-Fi and mobile networks. A refresh or a short signal drop brings a player back to the same game. After each game either player can ask for a rematch, and the player who moves first alternates.

How do 4x4 and 5x5 Tic Tac Toe work?

Bigger boards keep the same idea with a longer line to make. On the 4x4 board you need four in a row. On 5x5 you can choose between four in a row, which is open and tactical, and five in a row, which is the hardest and the closest to the game Gomoku.

Two things change. First, an open three is dangerous, because it can be finished from either end, so you must block it at once. Second, forks are much easier to build because there is more room, so the player who gets the centre and keeps making two-way threats usually wins. Note that 4x4 with four in a row is a draw with perfect play, just like 3x3, but the extra room means humans slip up far more often.

Tip: On the larger boards, turn on Move hints to see the cells the computer rates highest. They are often the ones that build two lines at once.

What are the cute marks and themes?

Marks can be classic X and O strokes that draw themselves in, cute smiling faces that blink, or stars and hearts that pop onto the board. Four board themes change the colours: Paper, Chalkboard, Neon and Candy. Your choices are saved in the browser. Everything is drawn in the game itself, so it loads quickly, and if your device is set to reduce motion the animations are switched off.

Controls on phone, tablet and keyboard

Tap or click an empty square to place your mark. On a keyboard, use the arrow keys to move between squares and press Enter or Space to place a mark. On the 3x3 board the number keys 1 to 9 place a mark in the matching square, counting along the rows from the top left. Press U to undo, H to switch hints on or off and M to mute.

Every square is a labelled button, so the game works with a screen reader and with a keyboard alone. Undo is available against the computer and on one screen, and takes back your last move and the reply.

Is Tic Tac Toe good for kids and for the classroom?

It is a great first strategy game. Children learn to take turns, spot patterns, block a threat and plan one move ahead, and a game takes under a minute. Start on Easy, and when they always win, move to Medium and teach them about forks. A teacher can put the game on a shared screen and ask the class which move is best before anyone taps.

The same game also introduces the idea that some games can always be forced to a draw by the right player, which leads naturally to talking about strategy and computers.

Where does Tic Tac Toe come from?

Games of three in a row are very old. The Romans played a close relative called terni lapilli, where each player had three pieces that they moved around the board. The paper-and-pencil version became widespread in the English-speaking world over the nineteenth century. In 1952 A. S. Douglas wrote OXO for the EDSAC computer in Cambridge, one of the earliest video games, and the game has been a classic test for computer opponents ever since.