Games like Check In Check Out
Games like Check In Check Out include SOMA, Layers of Fear (2016), What Remains of Edith Finch, No, I'm not a Human, and Outlast. We matched them by the tags players give Check In Check Out on Steam (Psychological Horror, Atmospheric, First-Person, Exploration, and Horror): closest matches first, and among equally close ones the better-known games.

SOMA
Shared: Psychological Horror · Atmospheric · Horror

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

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

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

Outlast
Shared: First-Person · Atmospheric · Psychological Horror

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

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

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

Scanner Sombre
Shared: Exploration · Atmospheric · Horror

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

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

Inside the Backrooms
Shared: Psychological Horror · Horror · Exploration

Firewatch
Shared: Atmospheric · First-Person · Walking Simulator

The Exit 8
Shared: Exploration · Psychological Horror · Horror

Garten of Banban
Shared: Psychological Horror · First-Person · Horror

MiSide
Shared: Psychological Horror · First-Person · Horror

Mouthwashing
Shared: Psychological Horror · Atmospheric · Horror

DON'T SCREAM
Shared: Psychological Horror · Atmospheric · First-Person

Phasmophobia
Shared: Psychological Horror · Horror · First-Person

ROUTINE
Shared: Psychological Horror · Atmospheric · Horror

Visage
Shared: Psychological Horror · Horror · First-Person

The Bridge Curse Road to Salvation
Shared: First-Person · Horror · Psychological Horror

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

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