Games like Fatberg
Games like Fatberg include Ready or Not, Outlast, Trepang2, Resident Evil 7 Biohazard, and Mouthwashing. We matched them by the tags players give Fatberg on Steam (Psychological Horror, Action, Retro, Atmospheric, and Singleplayer): closest matches first, and among equally close ones the better-known games.

Ready or Not
Shared: Singleplayer · Shooter · Psychological Horror

Outlast
Shared: Psychological Horror · Horror · Atmospheric

Trepang2
Shared: Singleplayer · Action · Shooter

Resident Evil 7 Biohazard
Shared: Horror · Singleplayer · Psychological Horror

Mouthwashing
Shared: Psychological Horror · Atmospheric · Retro

METRO 2033 Redux
Shared: Atmospheric · Action · Horror

F.E.A.R.
Shared: Action · Horror · Singleplayer

Resident Evil Village
Shared: Action · Horror · Singleplayer

DOOM
Shared: Action · Shooter · FPS

Outlast 2
Shared: Psychological Horror · Horror · Singleplayer

Metro Exodus
Shared: Singleplayer · Action · Atmospheric

HROT
Shared: Retro · Action · Shooter

Black Mesa
Shared: Action · Singleplayer · Atmospheric

CULTIC
Shared: Action · Retro · Shooter

DUSK
Shared: Retro · Horror · Shooter

Call of Duty®
Shared: Action · Singleplayer · Shooter

METRO Last Light Redux
Shared: Action · Atmospheric · Horror

MiSide
Shared: Psychological Horror · Horror · Singleplayer

HOLE
Shared: Psychological Horror · Horror · Singleplayer

BioShock Infinite
Shared: Action · Singleplayer · Shooter

No, I'm not a Human
Shared: Psychological Horror · Horror · Singleplayer

Half-Life: Alyx
Shared: Horror · Action · Singleplayer

DOOM Eternal
Shared: Action · FPS · Singleplayer

F.E.A.R. 2: Project Origin
Shared: Action · Horror · Singleplayer