Games like Great Toilet Simulator
Games like Great Toilet Simulator include Outlast, The Forest, Poppy Playtime, The Beast Inside, and We Happy Few. We matched them by the tags players give Great Toilet Simulator on Steam (Indie, Simulation, Horror, Action, and Adventure): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · First-Person · Singleplayer

The Forest
Shared: Horror · Adventure · Survival

Poppy Playtime
Shared: Horror · Singleplayer · First-Person

The Beast Inside
Shared: Horror · Adventure · Action

We Happy Few
Shared: Adventure · Action · Indie

Bendy and the Dark Revival
Shared: Horror · Action · Singleplayer

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

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

Firewatch
Shared: Adventure · Indie · Singleplayer

The Hat Man: Shadow Ward
Shared: Indie · Horror · Adventure

Bum Simulator
Shared: Simulation · Action · Adventure

The Long Dark
Shared: Survival · Singleplayer · Adventure

Lethal Company
Shared: Horror · First-Person · Indie

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

Thief Simulator
Shared: Simulation · Singleplayer · First-Person

Dark Deception
Shared: Horror · Singleplayer · Indie

Outlast 2
Shared: Horror · First-Person · Singleplayer

Spooky's Jump Scare Mansion: HD Renovation
Shared: Indie · Horror · Adventure

Crime Scene Cleaner
Shared: Simulation · Singleplayer · First-Person

Resident Evil Village
Shared: Horror · Action · Singleplayer

Ultimate Custom Night
Shared: Horror · Singleplayer · Indie

MiSide
Shared: Horror · Singleplayer · First-Person

Slender: The Arrival
Shared: Horror · Indie · First-Person

Totally Accurate Battle Simulator
Shared: Simulation · Indie · Singleplayer