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penumbra series, overture and black plague specifically. they're graphically and mechanically dated, but still some of the best atmospheric horror games ever made. it's the first attempt at survival horror by the people who would ultimately make amnesia (and i actually think they're far superior to amnesia, which had too many annoying mechanics that made it hard to navigate the game world). penumbra laid the foundation for stuff like alien: isolation, outlast, etc.
if you need something more modernized try soma. also the same producers, but it's a different setting and more polished experience.