Games like Thou Shalt Not Kill
Games like Thou Shalt Not Kill include Summer of '58, MiSide, Fears to Fathom - Ironbark Lookout, Mouthwashing, and What Remains of Edith Finch. We matched them by the tags players give Thou Shalt Not Kill on Steam (Psychological Horror, Horror, 3D, Atmospheric, and Realistic): closest matches first, and among equally close ones the better-known games.

Summer of '58
Shared: Horror · Psychological Horror · Atmospheric

MiSide
Shared: Psychological Horror · Horror · 3D

Fears to Fathom - Ironbark Lookout
Shared: Psychological Horror · Horror · Atmospheric

Mouthwashing
Shared: Psychological Horror · Horror · Atmospheric

What Remains of Edith Finch
Shared: Atmospheric · Exploration · First-Person

SOMA
Shared: Psychological Horror · Horror · Atmospheric

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

September 7th
Shared: Horror · Psychological Horror · Exploration

Firewatch
Shared: Atmospheric · First-Person · Exploration

SILENT HILL f
Shared: Psychological Horror · Horror · Female Protagonist

Backrooms: Escape Together
Shared: Horror · Psychological Horror · Atmospheric

Subliminal
Shared: Psychological Horror · Realistic · Atmospheric

Lethal Company
Shared: Horror · Psychological Horror · First-Person

SILENT HILL 2
Shared: Psychological Horror · Horror · Atmospheric

Psalm 5:9-13
Shared: Psychological Horror · Horror · Exploration

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

Still Wakes the Deep
Shared: Psychological Horror · Horror · First-Person

The Exit 8
Shared: Horror · Psychological Horror · Exploration

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

The Lightkeeper
Shared: Horror · Psychological Horror · Atmospheric

Martha Is Dead
Shared: Psychological Horror · Horror · Atmospheric

Outlast
Shared: Horror · Psychological Horror · Atmospheric

Escape the Backrooms
Shared: Horror · Psychological Horror · First-Person

Phasmophobia
Shared: Horror · Psychological Horror · First-Person