Games like The Shattering
Games like The Shattering include Firewatch, Mouthwashing, MiSide, What Remains of Edith Finch, and Layers of Fear (2016). We matched them by the tags players give The Shattering on Steam (Adventure, Indie, Thriller, Atmospheric, and Psychological): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Atmospheric · Story Rich

Mouthwashing
Shared: Atmospheric · Indie · Horror

MiSide
Shared: Story Rich · First-Person · Horror

What Remains of Edith Finch
Shared: Atmospheric · Adventure · Story Rich

Layers of Fear (2016)
Shared: Atmospheric · Horror · Indie

The Beginner's Guide
Shared: Indie · Atmospheric · Story Rich

Fears to Fathom - Ironbark Lookout
Shared: Atmospheric · Thriller · Adventure

No, I'm not a Human
Shared: Indie · Horror · Atmospheric

Blair Witch
Shared: Adventure · Indie · Horror

Hellblade: Senua's Sacrifice
Shared: Atmospheric · Psychological · Adventure

Detention
Shared: Indie · Atmospheric · Adventure

Outlast
Shared: Atmospheric · First-Person · Horror

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

Little Nightmares
Shared: Adventure · Atmospheric · Horror

SOMA
Shared: Atmospheric · Horror · Story Rich

The Park®
Shared: Adventure · Horror · Atmospheric

The Stanley Parable
Shared: Indie · Psychological · First-Person

Still Wakes the Deep
Shared: Horror · First-Person · Adventure

INMOST
Shared: Indie · Adventure · Atmospheric

Sally Face - Episode One
Shared: Indie · Adventure · Story Rich

Fran Bow
Shared: Adventure · Indie · Story Rich

Little Nightmares II
Shared: Adventure · Horror · Atmospheric

[Chillas Art] The Convenience Store
Shared: Indie · Adventure · Horror

Fears to Fathom® - Scratch Creek
Shared: Adventure · Horror · Indie

