Games like Debris
Games like Debris include The Beginner's Guide, Firewatch, What Remains of Edith Finch, Before Your Eyes, and Summerland. We matched them by the tags players give Debris on Steam (Walking Simulator, Story Rich, Interactive Fiction, Underwater, and Adventure): closest matches first, and among equally close ones the better-known games.

The Beginner's Guide
Shared: Walking Simulator · Story Rich · Atmospheric

Firewatch
Shared: Story Rich · Walking Simulator · Adventure

What Remains of Edith Finch
Shared: Story Rich · Walking Simulator · Atmospheric

Before Your Eyes
Shared: Story Rich · Interactive Fiction · Walking Simulator

Summerland
Shared: Story Rich · Walking Simulator · Adventure

DEATH STRANDING DIRECTOR'S CUT
Shared: Story Rich · Walking Simulator · Atmospheric

Gone Home
Shared: Walking Simulator · Story Rich · Atmospheric

The Stanley Parable
Shared: Walking Simulator · Adventure · Psychological

Hellblade: Senua's Sacrifice
Shared: Story Rich · Atmospheric · Psychological

The Forgotten City
Shared: Adventure · Story Rich · Investigation

Amnesia: A Machine For Pigs
Shared: Walking Simulator · Story Rich · Atmospheric

Mouthwashing
Shared: Story Rich · Atmospheric · Walking Simulator

To the Moon
Shared: Story Rich · Adventure · Interactive Fiction

KARMA: The Dark World
Shared: Walking Simulator · Atmospheric · Story Rich

Killer Frequency
Shared: Interactive Fiction · Adventure · Walking Simulator

The Talos Principle
Shared: Story Rich · Philosophical · Atmospheric

The Witcher 3: Wild Hunt — Remastered
Shared: Story Rich · Atmospheric · Adventure

Layers of Fear (2016)
Shared: Walking Simulator · Atmospheric · Story Rich

Journey
Shared: Adventure · Atmospheric · Walking Simulator

A Bird Story
Shared: Story Rich · Adventure · Interactive Fiction

OneShot
Shared: Story Rich · Atmospheric · Adventure

Where The Water Tastes Like Wine
Shared: Story Rich · Adventure · Interactive Fiction

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

CARIMARA: Beneath the forlorn limbs
Shared: Story Rich · Adventure · Walking Simulator