Games like Psychomachia - Nightvision
Games like Psychomachia - Nightvision include Outlast, Outlast 2, Mouthwashing, Blair Witch, and Amnesia: The Dark Descent. We matched them by the tags players give Psychomachia - Nightvision on Steam (Adventure, Indie, Gore, Violent, and Psychological): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · Gore · First-Person

Outlast 2
Shared: Horror · Gore · Psychological Horror

Mouthwashing
Shared: Indie · Horror · Psychological Horror

Blair Witch
Shared: Adventure · Indie · Horror

Amnesia: The Dark Descent
Shared: Gore · Horror · Psychological Horror

Scorn
Shared: Gore · Horror · Atmospheric

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

Fran Bow
Shared: Adventure · Psychological Horror · Indie

SOMA
Shared: Horror · Psychological Horror · Gore

Buckshot Roulette
Shared: Horror · Indie · Dark

Still Wakes the Deep
Shared: Gore · Horror · Psychological Horror

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

FAITH: The Unholy Trinity
Shared: Indie · Horror · Psychological Horror

Resident Evil 7 Biohazard
Shared: Horror · Gore · First-Person

Raging Loop
Shared: Adventure · Indie · Psychological Horror

[Chillas Art] Night Delivery
Shared: Indie · Adventure · Horror

The Beast Inside
Shared: Adventure · Horror · First-Person

Little Nightmares
Shared: Adventure · Horror · Indie

Poppy Playtime
Shared: Horror · First-Person · Indie

Detention
Shared: Indie · Horror · Adventure

Visage
Shared: Horror · Psychological Horror · Adventure

MADiSON
Shared: Horror · Psychological Horror · Adventure

Welcome to Kowloon
Shared: Adventure · Horror · Psychological Horror

The Medium
Shared: Adventure · Horror · Psychological Horror