Games like Tarpit
Games like Tarpit include Outlast, Poppy Playtime, No, I'm not a Human, Sally Face - Episode One, and Firework. We matched them by the tags players give Tarpit on Steam (Indie, Horror, Psychological Horror, Action, and Supernatural): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · Psychological Horror · Atmospheric

Poppy Playtime
Shared: Horror · Psychological Horror · Singleplayer

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

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

Firework
Shared: Indie · Horror · Psychological Horror

Mouthwashing
Shared: Horror · Psychological Horror · Indie

[Chillas Art] The Convenience Store
Shared: Indie · Horror · Psychological Horror

Firewatch
Shared: Atmospheric · Adventure · Indie

Phasmophobia
Shared: Horror · Psychological Horror · Supernatural

Ready or Not
Shared: Horror · Psychological Horror · Realistic

Little Nightmares
Shared: Horror · Atmospheric · Indie

The Beast Inside
Shared: Horror · Adventure · Action

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

Alan Wake
Shared: Horror · Action · Adventure

MiSide
Shared: Psychological Horror · Horror · Atmospheric

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

The Room Two
Shared: Horror · Indie · Atmospheric

Outlast 2
Shared: Horror · Psychological Horror · Atmospheric

Resident Evil 7 Biohazard
Shared: Horror · Psychological Horror · Atmospheric

SOMA
Shared: Horror · Psychological Horror · Atmospheric

Five Nights at Freddy's
Shared: Horror · Indie · Psychological Horror

Little Nightmares II
Shared: Horror · Adventure · Psychological Horror

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

Escape the Backrooms
Shared: Horror · Psychological Horror · Adventure