Noughts and crosses – also known as tic-tac-toe – isn’t a very interesting game. To play it, you draw a three-by-three grid, then take it in turns with another player to fill in a square with your mark: X or O. The winner is the first person to get three in a row. If you know what you’re doing, however, this should never happen. So long as nobody makes a mistake, the result will always be a draw.
I know this because noughts and crosses is a ‘solved game’: one whose outcome can correctly be predicted at every stage, so long as both players play perfectly. It’s simple enough that most children can do
