Snake

Snake is the arcade classic that came bundled on a generation of phones, and it still works because the difficulty is entirely self-inflicted. You steer a constantly moving line around the board, eating dots to grow — and every dot you eat makes the very thing you are trying to avoid, your own tail, longer and harder to dodge. There is no level to beat and no timer, just the slow, rising pressure of a board you are steadily filling with yourself. Early on it is relaxing; a few hundred points in, a single wrong turn ends the run, and that is exactly the hook. Good play is about leaving yourself escape routes and running tidy edges rather than greedily cutting across the middle. This version has crisp keyboard and swipe controls and saves your best length, so there is always a number to beat. It loads instantly, works on any screen, and asks nothing of you but one more attempt.