Nine Morris

Nine Morris is Nine Men's Morris, cut into a plank of walnut: three squares inside one another, joined at the middles, twenty-four points where the lines meet. You play the brass men, your opponent the dark river stone. The game opens with your hands full — nine men each, set down one at a time on any free point — and the board fills up faster than you expect.

Three of your men in a row along one line is a mill, and closing one lets you lift an enemy man off the board there and then. You cannot take a man that stands inside a mill unless every man they have left is in one, which is why the good players build two mills that share a point and swing a man back and forth between them, taking a piece every single turn. Once the hands are empty a turn means sliding a man to a neighbouring free point, so the board tightens and blocking becomes as useful as capturing. A side worn down to three men earns the right to fly: move to any free point at all, which turns a lost position into a last chase. Two men left, or no legal move, and it is over.

Play against a brain with three settings — Easy wanders, Normal looks a couple of moves ahead, and Sharp runs a small minimax with alpha-beta pruning, so it sees the double mill coming. Or pick two players and pass the screen back and forth with someone beside you. Legal points glow while you are learning, undo takes back a rash move, the full rules sit one tap away, and your wins and losses are kept in the browser between visits.