Last Sanctuary

Shelter 73 leaves you with one iron door, one peephole, and a Rule Manual full of red ink. Three knocks mean living. Two knocks mean mimic. No knocks mean never open. Then the first visitor fogs the glass while the vent grille tilts wrong. Across 100 days, the rules twist, the manual thins, and every choice asks the same thing: are you guarding the shelter, or guarding the world from you?