Parking Jam

The familiar gridlocked-lot format: cars packed bumper to bumper, one exit, and a puzzle in figuring out which vehicle to move first so it doesn't trap everyone behind it. Cars slide forward and backward along their own line only, never sideways, which is what keeps this from turning into a free-for-all. Boards get denser as you go, and a few later levels genuinely need you to back a car up before it can go anywhere.