Games like Grandmother
Games like Grandmother include The Outlast Trials, Five Nights at Freddy's: Security Breach, Escape the Backrooms, Outlast, and Resident Evil Village. We matched them by the tags players give Grandmother on Steam (Horror, Action, Hidden Object, PvE, and Stealth): closest matches first, and among equally close ones the better-known games.

The Outlast Trials
Shared: Horror · PvE · First-Person

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

Escape the Backrooms
Shared: Horror · First-Person · Action

Outlast
Shared: Horror · First-Person · Survival Horror

Resident Evil Village
Shared: Horror · Action · First-Person

Resident Evil Requiem
Shared: Horror · Action · Survival Horror

Lethal Company
Shared: Horror · First-Person · PvE

Bendy and the Dark Revival
Shared: Horror · Action · First-Person

R.E.P.O.
Shared: Horror · First-Person · 3D

Dying Light
Shared: Horror · First-Person · Action

Ready or Not
Shared: Horror · Realistic · Action

Dead by Daylight
Shared: Horror · Survival Horror · Stealth

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

The Forest
Shared: Horror · Action · First-Person

Metel - Horror Escape
Shared: Horror · Hidden Object · Action

Resident Evil 4
Shared: Horror · Action · Survival Horror

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

Alien: Isolation
Shared: Horror · Stealth · First-Person

METRO Last Light Redux
Shared: Action · Horror · First-Person

Poppy Playtime
Shared: Horror · First-Person · Singleplayer

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

Zort
Shared: Horror · PvE · Action

METRO 2033 Redux
Shared: Horror · Action · First-Person

Amnesia: The Bunker
Shared: Horror · Stealth · First-Person