Games like Opus Castle
Games like Opus Castle include Far Cry® 5, Darkwood, Five Nights at Freddy's: Security Breach, SILENT HILL f, and Metro Exodus. We matched them by the tags players give Opus Castle on Steam (Exploration, FPS, 3D, Action-Adventure, and Historical): closest matches first, and among equally close ones the better-known games.

Far Cry® 5
Shared: Action-Adventure · FPS · Exploration

Darkwood
Shared: Horror · Psychological Horror · Exploration

Five Nights at Freddy's: Security Breach
Shared: Horror · Exploration · 3D

SILENT HILL f
Shared: Horror · Psychological Horror · Story Rich

Metro Exodus
Shared: FPS · Story Rich · Horror

Assassin's Creed® Odyssey
Shared: Action-Adventure · Exploration · Historical

SILENT HILL 2
Shared: Horror · Psychological Horror · Story Rich

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

Resident Evil Requiem
Shared: FPS · Horror · Action-Adventure

The Dark Pictures Anthology: House of Ashes
Shared: Horror · Action-Adventure · Psychological Horror

Escape the Backrooms
Shared: Horror · Exploration · Psychological Horror

Inside the Backrooms
Shared: Horror · Exploration · Psychological Horror

SOMA
Shared: Horror · Psychological Horror · Exploration

MiSide
Shared: Psychological Horror · Horror · 3D

Five Nights at Freddy's: Secret of the Mimic
Shared: Horror · Exploration · 3D

METRO 2033 Redux
Shared: FPS · Horror · Story Rich

Outer Wilds
Shared: Exploration · Story Rich · Adventure

In Sound Mind
Shared: Horror · Psychological Horror · Story Rich

Indiana Jones and the Great Circle
Shared: Action-Adventure · Exploration · Story Rich

S.T.A.L.K.E.R. 2: Heart of Chornobyl - Standard Edition
Shared: FPS · Exploration · Story Rich

Incantation
Shared: Exploration · Horror · Action-Adventure

A Plague Tale: Requiem
Shared: Exploration · Action-Adventure · 3D

The Shore
Shared: Exploration · FPS · Horror

Crisol: Theater of Idols
Shared: FPS · Action-Adventure · Horror