Games like Insomnis
Games like Insomnis include Poppy Playtime, Inside the Backrooms, Amnesia: The Dark Descent, Escape the Backrooms, and Lethal Company. We matched them by the tags players give Insomnis on Steam (Adventure, Indie, Horror, Action-Adventure, and Puzzle): closest matches first, and among equally close ones the better-known games.

Poppy Playtime
Shared: Horror · Puzzle · First-Person

Inside the Backrooms
Shared: Horror · Puzzle · Adventure

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

Escape the Backrooms
Shared: Horror · Psychological Horror · Adventure

Lethal Company
Shared: Horror · First-Person · Exploration

Amnesia: Rebirth
Shared: Action-Adventure · Puzzle · Adventure

Backrooms: Escape Together
Shared: Horror · Psychological Horror · First-Person

Outer Wilds
Shared: Adventure · Exploration · Puzzle

Outlast
Shared: Horror · First-Person · Psychological Horror

SOMA
Shared: Horror · Psychological Horror · Exploration

Five Nights at Freddy's: Security Breach
Shared: Horror · First-Person · Adventure

Little Nightmares II
Shared: Adventure · Horror · Puzzle

Hello Neighbor 2
Shared: Adventure · Horror · Puzzle

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

The Beast Inside
Shared: Adventure · Horror · First-Person

The Exit 8
Shared: Horror · Puzzle · Exploration

The Forest
Shared: Horror · Adventure · First-Person

The Death | Thần Trùng
Shared: Horror · Indie · Adventure

Lorelei and the Laser Eyes
Shared: Adventure · Puzzle · Horror

Five Nights at Freddy's: Secret of the Mimic
Shared: Adventure · Horror · First-Person

Ghost Watchers
Shared: Horror · Adventure · Puzzle

Fran Bow
Shared: Adventure · Horror · Puzzle

Bendy and the Ink Machine
Shared: Horror · Puzzle · First-Person

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