Eli: The Unhuman

A poisonous fog swallows the Kingdom of Ravengale overnight, and by morning it's a killer with no known cure. That's the setup, and it's grim rather than cute about it.

The fog retreats to the city's edges after dark, but the streets aren't empty. Humanoid creatures wearing the shape of women pour out to hunt whoever's left outside, and what happens next depends on who they catch. Women get killed or turned into more of them; men get raped to death. Houses are safe, supposedly, unless you're unlucky enough to be alone in one.

Survival here means staying inside and picking your moments to move, with the sandbox structure giving you a city to navigate around a curfew that actively wants you dead. Multiple endings suggest the choices you make about when to hide and when to risk the fog actually matter, though the source doesn't spell out how deep that branching goes.