Nothing on this ice stops on its own. Park the red stone on the target in as few slides as the machine.
Every stone slides in a straight line until it hits a wall or another stone. There is no braking. Get the red stone (1) to stop exactly on the ringed target. Blue and gold stones are yours to use as bumpers: a stone parked in the right place becomes a wall.
The "Machine" number is the true minimum, found by a breadth-first search over every position the stones can reach. Three stars for matching it, two for within two slides, one for anything else. A hint costs you the top two stars.
Controls: 1 2 3 or Tab pick a stone, arrow keys or WASD slide it, Z undo, R restart, H hint, L landing marks. On a touch screen, tap a stone and swipe, or tap an empty square in line with it.
Levels are generated from fixed seeds, so everyone gets the same 20 boards. No data leaves your browser.