Here’s my super short description for those that have never played.

Draw a grid of dots on some blank paper. Your X, your friend is O.

Start by drawing a line between two adjacent dots, no diagonals (this is a wall). Take it in turns to draw a line between two adjacent dots.

If you draw a line that closes a square (or two!)(the smallest possible square), claim the closed square/s by writing a X inside the claimed square.

Game ends when nothing more to draw, count up your symbols for the winner.