Games like Unfeigned Depths
Games like Unfeigned Depths include Mouthwashing, Outlast, SOMA, No, I'm not a Human, and MiSide. We matched them by the tags players give Unfeigned Depths on Steam (Horror, Psychological Horror, Atmospheric, Dark, and Action): closest matches first, and among equally close ones the better-known games.

Mouthwashing
Shared: Horror · Psychological Horror · Atmospheric

Outlast
Shared: Horror · Atmospheric · Psychological Horror

SOMA
Shared: Horror · Psychological Horror · Atmospheric

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

MiSide
Shared: Psychological Horror · Horror · First-Person

Poppy Playtime
Shared: Horror · Psychological Horror · First-Person

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

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

Hellblade: Senua's Sacrifice
Shared: Atmospheric · Psychological · Horror

Outlast 2
Shared: Horror · Psychological Horror · First-Person

Little Nightmares II
Shared: Horror · Dark · Atmospheric

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

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

Alan Wake
Shared: Horror · Action · Atmospheric

Darkwood
Shared: Horror · Psychological Horror · Action

Phasmophobia
Shared: Horror · Psychological Horror · First-Person

SILENT HILL 2
Shared: Horror · Psychological Horror · Atmospheric

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

Visage
Shared: Horror · Psychological Horror · Dark

The Outlast Trials
Shared: Horror · Psychological Horror · First-Person

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

Buckshot Roulette
Shared: Horror · Dark · First-Person

Little Nightmares
Shared: Horror · Atmospheric · Dark

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