Tic tac toe
You are X and you go first; the computer is O. Move between squares with Tab and play one with Enter or Space.
The board
Nothing is saved: no scores, no progress, no cookies. Reload and the game starts again.
About this game
How to play
- The board is three squares by three. You are X and always go first; the computer is O.
- Take turns putting one mark in an empty square. A square, once taken, stays taken.
- The first to get three marks in a line — across, down or corner to corner — wins.
- If all nine squares fill up with no line of three, the game is a draw. Press New game to play again.
What the three levels change
- Easy
- The computer picks any free square at random. You should win most games.
- Medium
- The computer takes a win when it sees one and blocks yours when it must; otherwise it prefers the centre, then a corner, then a side. A careful player can always draw, and a sharp one can win.
- Hard
- The computer checks every way the game could go before each move. It never loses: the best you can do is a draw.
Keyboard and screen readers
- Tab and Shift+Tab move between the nine squares. Enter or Space plays the square you are on.
- Each square has a name that says where it is and what is in it, such as “Row 2, column 3: empty”. Taken squares stay in the Tab order, so you can check them.
- Your moves, the computer’s replies and the result are read out from the line under the board. The winning line is marked by shape, not only by colour.
An odd fact about this game
Noughts and crosses was one of the very first video games. In 1952 Sandy Douglas, a student at the University of Cambridge, wrote OXO for the EDSAC computer. Players chose their square with a telephone dial, and the machine could play a perfect game.
Source: Wikipedia: OXO (video game)