Games like Nightmare Hospital
Games like Nightmare Hospital include Firewatch, Outlast, SOMA, What Remains of Edith Finch, and Still Wakes the Deep. We matched them by the tags players give Nightmare Hospital on Steam (Horror, Adventure, Atmospheric, Dark, and Exploration): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Atmospheric · Walking Simulator

Outlast
Shared: Horror · Atmospheric · First-Person

SOMA
Shared: Horror · Atmospheric · Dark

What Remains of Edith Finch
Shared: Atmospheric · Adventure · Walking Simulator

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

Layers of Fear (2016)
Shared: Horror · Atmospheric · First-Person

Visage
Shared: Horror · Dark · Atmospheric

Summer of '58
Shared: Horror · Atmospheric · First-Person

Mouthwashing
Shared: Horror · Atmospheric · Dark

Amenti
Shared: Horror · Adventure · Dark

ROUTINE
Shared: Atmospheric · Adventure · Horror

Obey the Voice™
Shared: Horror · Adventure · Atmospheric

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

Little Nightmares
Shared: Horror · Adventure · Atmospheric

Welcome to Kowloon
Shared: Horror · Atmospheric · Adventure

Poppy Playtime
Shared: Horror · First-Person · Dark

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

Amnesia: A Machine For Pigs
Shared: Horror · Atmospheric · Walking Simulator

Amnesia: The Dark Descent
Shared: Horror · Atmospheric · First-Person

Little Nightmares II
Shared: Horror · Adventure · Dark

The Forest
Shared: Horror · Adventure · First-Person

Outlast 2
Shared: Horror · First-Person · Dark

Bramble: The Mountain King
Shared: Horror · Adventure · Atmospheric

Buckshot Roulette
Shared: Horror · Dark · First-Person