Take turns drawing one line between two dots. You draw green and the computer draws pink. When your line finishes the fourth side of a box, you claim that box and go again. Be careful: a line that makes the third side of a box lets the other player grab it. Whoever claims the most boxes wins. Pick a 3x3, 4x4 or 5x5 board and an Easy, Normal or Hard computer.
Try a line on a separate board. The example takes every available box in order; Easy AI may miss one, and Hard AI may deliberately decline a capture.
Choose a line, then explore its capture chain.