If you have five spare minutes, Snake Insane will fill them. Everything happens on one screen with a starting step of 90 ms that tightens as you eat, and the whole thing runs straight in the browser - no downloads, no sign-ups, no fuss.
Steering is the whole game: swipes on touch, arrow keys or WASD on desktop. The input queue accepts two turns ahead, which means a well-timed double turn can thread a gap that looks impossible at first glance.
It suits anyone with a queue to wait in or a kettle to watch: students between classes, commuters, parents stealing ten quiet minutes. There is no meta-progression to lose and nothing to catch up on - a week away costs you nothing but a little sharpness.