Games like Room Service
Games like Room Service include No, I'm not a Human, Mouthwashing, Poppy Playtime, Sally Face - Episode One, and Little Nightmares II. We matched them by the tags players give Room Service on Steam (Psychological Horror, Psychological, Singleplayer, Atmospheric, and Horror): closest matches first, and among equally close ones the better-known games.

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

Mouthwashing
Shared: Psychological Horror · Horror · Atmospheric

Poppy Playtime
Shared: Singleplayer · Horror · Psychological Horror

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

Little Nightmares II
Shared: Singleplayer · Horror · Psychological Horror

MiSide
Shared: Psychological Horror · Horror · Singleplayer

Little Nightmares
Shared: Atmospheric · Horror · Singleplayer

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

SOMA
Shared: Psychological Horror · Horror · Atmospheric

SILENT HILL 2
Shared: Psychological Horror · Horror · Psychological

Outlast
Shared: Psychological Horror · Horror · Atmospheric

Fran Bow
Shared: Psychological Horror · Horror · Singleplayer

DISTRAINT: Deluxe Edition
Shared: Psychological Horror · Horror · Atmospheric

Firewatch
Shared: Atmospheric · Singleplayer · Mystery

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

What Remains of Edith Finch
Shared: Atmospheric · Mystery · Singleplayer

Outlast 2
Shared: Psychological Horror · Horror · Singleplayer

Tiny Bunny
Shared: Horror · Psychological Horror · Atmospheric

Alan Wake
Shared: Horror · Psychological Horror · Atmospheric

Firework
Shared: Horror · Psychological Horror · Atmospheric

Phasmophobia
Shared: Psychological Horror · Horror · Dark

Subliminal
Shared: Psychological Horror · Singleplayer · Atmospheric

Garten of Banban
Shared: Singleplayer · Psychological Horror · Horror

Buckshot Roulette
Shared: Dark · Horror · Singleplayer