A Japanese "chess" of pure capture on a 9×9 board, each side lined up along a rank. Slide a stone like a rook, any distance in a straight line. Trap an AI stone — or a row of them — between two of yours and it is captured.
Captures only trigger on the stone you just moved, so you flank the enemy rather than them walking into it. Watch your own stones too — never leave one with an AI stone on one side and an open lane on the other, or the AI slides in and takes it.