Games like Testimony - Night Underground
Games like Testimony - Night Underground include Firewatch, What Remains of Edith Finch, Bad Parenting 1: Mr. Red Face, Who's at the door?, and MiSide. We matched them by the tags players give Testimony - Night Underground on Steam (Adventure, Simulation, Walking Simulator, 3D, and 1990's): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Walking Simulator · Mystery

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

Bad Parenting 1: Mr. Red Face
Shared: Adventure · Walking Simulator · 1990's

Who's at the door?
Shared: Adventure · Simulation · Walking Simulator

MiSide
Shared: 3D · Psychological Horror · Horror

Dollmare
Shared: Simulation · 3D · Walking Simulator

Dread Flats
Shared: Adventure · Mystery · Supernatural

Oxenfree
Shared: Adventure · Supernatural · Mystery

Platform 8
Shared: Adventure · Walking Simulator · Simulation

Murdered: Soul Suspect
Shared: Adventure · Mystery · Supernatural

The Bridge Curse 2: The Extrication
Shared: Mystery · Stealth · Thriller

Alan Wake
Shared: Adventure · Horror · Thriller

A Plague Tale: Innocence
Shared: Adventure · Stealth · Story Rich

Little Nightmares II
Shared: Adventure · Horror · Stealth

SchoolBoy Runaway
Shared: Adventure · Simulation · Stealth

The Suicide of Rachel Foster
Shared: Walking Simulator · Adventure · Mystery

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

OXENFREE II: Lost Signals
Shared: Adventure · Mystery · Supernatural

The Mortuary Assistant
Shared: Mystery · Simulation · Supernatural

Fears to Fathom - Woodbury Getaway
Shared: Adventure · Walking Simulator · 1990's

The Complex: Expedition
Shared: Adventure · Horror · Mystery

Sally Face - Episode One
Shared: Adventure · Mystery · Psychological Horror

Millennium Dream
Shared: Adventure · Walking Simulator · 1990's

PARANORMASIGHT: The Seven Mysteries of Honjo
Shared: Adventure · Simulation · Horror