Games like STAMPED
Games like STAMPED include The Test, No, I'm not a Human, Sally Face - Episode One, The Test: Hypothesis Rising, and The Casting of Frank Stone™. We matched them by the tags players give STAMPED on Steam (Psychological Horror, Horror, Atmospheric, Investigation, and Dystopian ): closest matches first, and among equally close ones the better-known games.

The Test
Shared: Psychological Horror · Choose Your Own Adventure · Simulation

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

Sally Face - Episode One
Shared: Psychological Horror · Horror · Atmospheric

The Test: Hypothesis Rising
Shared: Horror · Psychological Horror · Simulation

The Casting of Frank Stone™
Shared: Horror · Psychological Horror · Atmospheric

Dagon: by H. P. Lovecraft
Shared: Horror · Atmospheric · Psychological Horror

The Test: Final Revelation
Shared: Horror · Psychological Horror · Choose Your Own Adventure

Tiny Bunny
Shared: Horror · Atmospheric · Psychological Horror

Slay the Princess — The Pristine Cut
Shared: Psychological Horror · Horror · Choose Your Own Adventure

Phasmophobia
Shared: Horror · Psychological Horror · Investigation

SOMA
Shared: Psychological Horror · Horror · Atmospheric

Mouthwashing
Shared: Psychological Horror · Horror · Atmospheric

Amnesia: A Machine For Pigs
Shared: Horror · Atmospheric · Psychological Horror

Little Nightmares
Shared: Horror · Atmospheric · Psychological Horror

Orwell: Keeping an Eye On You
Shared: Investigation · Dystopian · Simulation

MiSide
Shared: Psychological Horror · Horror · Atmospheric

Firework
Shared: Horror · Psychological Horror · Atmospheric

Oxenfree
Shared: Atmospheric · Horror · Mystery

Little Nightmares II
Shared: Horror · Psychological Horror · Atmospheric

SILENT HILL 2
Shared: Psychological Horror · Horror · Atmospheric

Iron Lung
Shared: Horror · Psychological Horror · Atmospheric

Layers of Fear (2016)
Shared: Psychological Horror · Horror · Atmospheric

DEAD LETTER DEPT.
Shared: Horror · Psychological Horror · Atmospheric

OMORI
Shared: Psychological Horror · Horror · Atmospheric