Games like Shellshock
Games like Shellshock include What Remains of Edith Finch, Firewatch, Platform 8, The Exit 8, and Scanner Sombre. We matched them by the tags players give Shellshock on Steam (Adventure, Simulation, Puzzle, Walking Simulator, and Exploration): closest matches first, and among equally close ones the better-known games.

What Remains of Edith Finch
Shared: Walking Simulator · Adventure · Exploration

Firewatch
Shared: Adventure · Walking Simulator · Atmospheric

Platform 8
Shared: Adventure · Simulation · Walking Simulator

The Exit 8
Shared: Puzzle · Exploration · Walking Simulator

Scanner Sombre
Shared: Walking Simulator · Adventure · Exploration

Outer Wilds
Shared: Adventure · Exploration · Puzzle

Killer Frequency
Shared: Adventure · Puzzle · Simulation

Inside the Backrooms
Shared: Puzzle · Adventure · Exploration

Riven
Shared: Adventure · Puzzle · Exploration

INFRA
Shared: Puzzle · Exploration · Adventure

The Witness
Shared: Puzzle · Exploration · First-Person

Layers of Fear (2016)
Shared: Walking Simulator · Adventure · First-Person

Quern - Undying Thoughts
Shared: Adventure · Puzzle · Exploration

MOLE
Shared: Simulation · Adventure · Puzzle

SOMA
Shared: Atmospheric · Exploration · Dark

Poppy Playtime
Shared: Puzzle · First-Person · Adventure

The Long Dark
Shared: Exploration · Adventure · First-Person

Blue Prince
Shared: Puzzle · Exploration · Adventure

PEAK
Shared: Adventure · Exploration · First-Person

POOLS
Shared: Walking Simulator · Exploration · Realistic

SnowRunner
Shared: Simulation · Adventure · Exploration

NaissanceE
Shared: Exploration · Adventure · Walking Simulator

Among the Sleep - Enhanced Edition
Shared: Adventure · Walking Simulator · First-Person

Obduction
Shared: Adventure · Puzzle · Exploration