PULSE

       A dot spins around a ring. Tap the instant it crosses the red zone — that's the whole game.
Hit near the centre of the zone for a perfect, worth triple. Every hit makes the zone smaller and the dot faster, and every so often it snaps into reverse just as you've found the rhythm. One miss ends the run.
Plays in your browser, on desktop or phone. Tap, click or hit space. Runs last about thirty seconds, which is the problem.
How to play — Tap anywhere to start. Tap when the dot is inside the red arc. Perfect hits give 3 points, normal hits give 1.