Games like Killer Santa 1990
Games like Killer Santa 1990 include Outlast, Mouthwashing, Amnesia: The Dark Descent, The Beast Inside, and SOMA. We matched them by the tags players give Killer Santa 1990 on Steam (Horror, Adventure, Psychological Horror, Retro, and Action): closest matches first, and among equally close ones the better-known games.

Outlast
Shared: Horror · Psychological Horror · Gore

Mouthwashing
Shared: Horror · Psychological Horror · Retro

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

The Beast Inside
Shared: Horror · Adventure · Action

SOMA
Shared: Horror · Psychological Horror · Gore

Escape the Backrooms
Shared: Horror · Psychological Horror · Adventure

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

Outlast 2
Shared: Horror · Psychological Horror · Gore

SILENT HILL: Townfall
Shared: Horror · Adventure · Psychological Horror

Still Wakes the Deep
Shared: Horror · Psychological Horror · Gore

The Forest
Shared: Horror · Adventure · Action

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

The Evil Within 2
Shared: Horror · Psychological Horror · Adventure

Poppy Playtime
Shared: Horror · Psychological Horror · Adventure

Fears to Fathom - Ironbark Lookout
Shared: Horror · Psychological Horror · Adventure

SILENT HILL f
Shared: Horror · Psychological Horror · Adventure

Darkwood
Shared: Horror · Adventure · Psychological Horror

The Outlast Trials
Shared: Horror · Psychological Horror · Action

MOLE
Shared: Horror · Adventure · Psychological Horror

Alan Wake
Shared: Horror · Action · Adventure

Resident Evil Village
Shared: Horror · Action · Gore

Fears to Fathom - Norwood Hitchhike
Shared: Horror · Psychological Horror · Retro

Nightmare of Decay
Shared: Horror · Action · 1990's

Fears to Fathom - Woodbury Getaway
Shared: Adventure · Horror · Psychological Horror