Games like The Killer
Games like The Killer include Outlast, Poppy Playtime, Resident Evil 7 Biohazard, Outlast 2, and MiSide. We matched them by the tags players give The Killer on Steam (Adventure, Horror, Survival, Indie, and Puzzle): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · First-Person · Psychological Horror

Poppy Playtime
Shared: Horror · Puzzle · First-Person

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

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

MiSide
Shared: Horror · Psychological Horror · First-Person

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

The Forest
Shared: Horror · Survival · Adventure

Little Nightmares II
Shared: Adventure · Horror · Puzzle

Little Nightmares
Shared: Horror · Adventure · Atmospheric

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

Scorn
Shared: Horror · Puzzle · Gore

MADiSON
Shared: Horror · Psychological Horror · Adventure

Inside the Backrooms
Shared: Horror · Puzzle · Adventure

Blair Witch
Shared: Adventure · Horror · Indie

Fran Bow
Shared: Horror · Adventure · Psychological Horror

Granny
Shared: Horror · Adventure · Puzzle

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

SOMA
Shared: Horror · Psychological Horror · Atmospheric

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

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

Dead by Daylight
Shared: Horror · Survival · Gore

Penumbra Overture
Shared: Adventure · Horror · Indie

We Happy Few
Shared: Adventure · Survival · Indie

Subnautica 2
Shared: Horror · Survival · Adventure