Games like The Ruins
Games like The Ruins include Poppy Playtime, Darkwood, Inside the Backrooms, Outlast, and Escape the Backrooms. We matched them by the tags players give The Ruins on Steam (Survival Horror, Dark, Adventure, Horror, and Action): closest matches first, and among equally close ones the better-known games.

Poppy Playtime
Shared: Horror · Survival Horror · Dark

Darkwood
Shared: Survival Horror · Horror · Adventure

Inside the Backrooms
Shared: Survival Horror · Horror · Adventure

Outlast
Shared: Survival Horror · Horror · Dark

Escape the Backrooms
Shared: Horror · Survival Horror · Adventure

SOMA
Shared: Horror · Dark · Survival Horror

Resident Evil Requiem
Shared: Survival Horror · Horror · Action

Bendy and the Ink Machine
Shared: Horror · Survival Horror · Dark

Amnesia: The Dark Descent
Shared: Survival Horror · Horror · Dark

Lethal Company
Shared: Horror · Survival Horror · Exploration

Bendy and the Dark Revival
Shared: Horror · Survival Horror · Action

Visage
Shared: Survival Horror · Horror · Dark

The Forest
Shared: Horror · Adventure · Survival Horror

Backrooms: Escape Together
Shared: Horror · Survival Horror · Psychological Horror

Resident Evil 4
Shared: Survival Horror · Horror · Action

Five Nights at Freddy's: Security Breach
Shared: Survival Horror · Horror · Adventure

Outlast 2
Shared: Survival Horror · Horror · Dark

Pacify
Shared: Horror · Survival Horror · Dark

Buckshot Roulette
Shared: Dark · Horror · Strategy

The Outlast Trials
Shared: Survival Horror · Horror · Action

Garten of Banban
Shared: Horror · Survival Horror · Dark

Slender: The Arrival
Shared: Survival Horror · Horror · Dark

The Beast Inside
Shared: Adventure · Survival Horror · Horror

Little Nightmares
Shared: Horror · Adventure · Dark