Click anywhere to put a coin in and start it spinning; click again to stop the reels. Three counters across the top track coins, gems and spins. The reels are emoji, and the machine is round rather than the usual three windows in a row, so the symbols come past on a curve.
It is a toy rather than a game, and it knows it. There is no way to run out and nothing is being wagered. What it has is the timing: stopping the reels yourself turns an idle animation into something you can be good at, or at least believe you can be good at, which as anyone who has stood in front of one of these knows is the same thing.