Some games only need a single good idea to work. For example: Superhot, a punishing first-person shooter in which time only moves when you move. It’s a single, good idea. And it works.
An army of faceless enemies waits in ambush, or maybe they jog into the room in waves, or maybe they creep up behind you. Most of them are armed with some sort of gun or other weapon, and a single hit from any of them will kill you. Your substantial advantage is that if you stop moving, time slows to a crawl. Bullets edge toward you inch by inch; katana-wielding foes move like snails. You have time to plan, prioritize, and then act.