Games like Somnium
Games like Somnium include SchoolBoy Runaway, The Room, The Room Three, The Room 4: Old Sins, and The Room Two. We matched them by the tags players give Somnium on Steam (Simulation, Adventure, Puzzle, Hidden Object, and 3D): closest matches first, and among equally close ones the better-known games.

SchoolBoy Runaway
Shared: Adventure · Simulation · Puzzle

The Room
Shared: Puzzle · Adventure · Hidden Object

The Room Three
Shared: Puzzle · Adventure · Mystery

The Room 4: Old Sins
Shared: Puzzle · Adventure · Mystery

The Room Two
Shared: Puzzle · Hidden Object · Adventure

Platform 8
Shared: Adventure · Simulation · Puzzle

Return of the Obra Dinn
Shared: Puzzle · Detective · Mystery

Poppy Playtime
Shared: Puzzle · First-Person · Adventure

The House of Da Vinci
Shared: Puzzle · Hidden Object · Adventure

Blue Prince
Shared: Puzzle · Mystery · Adventure

Strange Horticulture
Shared: Puzzle · Simulation · Mystery

Escape Simulator
Shared: Puzzle · Adventure · First-Person

Buckshot Roulette
Shared: First-Person · 3D · Puzzle

Car Mechanic Simulator 2021
Shared: Simulation · Realistic · 3D

Totally Accurate Battle Simulator
Shared: Simulation · Adventure · Realistic

Boxes: Lost Fragments
Shared: Puzzle · Adventure · 3D

Murders on the Yangtze River
Shared: Adventure · Puzzle · Detective

Outer Wilds
Shared: Adventure · Puzzle · Mystery

Chants of Sennaar
Shared: Adventure · Puzzle · Indie

Cyber Manhunt
Shared: Simulation · Puzzle · Detective

Metel - Horror Escape
Shared: Puzzle · 3D · Hidden Object

Contraband Police
Shared: Simulation · First-Person · Realistic

Sherlock Holmes: The Devil's Daughter
Shared: Adventure · Puzzle · Detective

Internet Cafe Simulator 2
Shared: Simulation · 3D · First-Person