Games like Lost Brothers
Games like Lost Brothers include Firewatch, What Remains of Edith Finch, The Beginner's Guide, Gone Home, and Brothers - A Tale of Two Sons. We matched them by the tags players give Lost Brothers on Steam (Walking Simulator, First-Person, Atmospheric, Emotional, and Adventure): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Atmospheric · Walking Simulator · Adventure

What Remains of Edith Finch
Shared: Walking Simulator · Atmospheric · First-Person

The Beginner's Guide
Shared: Walking Simulator · Atmospheric · First-Person

Gone Home
Shared: Walking Simulator · Atmospheric · First-Person

Brothers - A Tale of Two Sons
Shared: Atmospheric · Adventure · Emotional

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

Amnesia: A Machine For Pigs
Shared: Walking Simulator · Atmospheric · First-Person

Before Your Eyes
Shared: Emotional · First-Person · Walking Simulator

The Witness
Shared: First-Person · Singleplayer · Atmospheric

The Room
Shared: Atmospheric · Adventure · Singleplayer

The Stanley Parable
Shared: Walking Simulator · First-Person · Indie

A Story About My Uncle
Shared: First-Person · Adventure · Atmospheric

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

Valley
Shared: First-Person · Adventure · Singleplayer

Outer Wilds
Shared: Adventure · Atmospheric · Mystery

Riven
Shared: First-Person · Adventure · Atmospheric

Journey
Shared: Atmospheric · Adventure · Walking Simulator

The Vanishing of Ethan Carter
Shared: Atmospheric · Walking Simulator · First-Person

The Long Dark
Shared: Atmospheric · First-Person · Singleplayer

Fallout 4
Shared: Singleplayer · Atmospheric · Adventure

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

INFRA
Shared: Atmospheric · First-Person · Walking Simulator

Call of the Sea
Shared: First-Person · Adventure · Atmospheric

Everybody's Gone to the Rapture
Shared: Walking Simulator · Atmospheric · Adventure