Games like Underwater
Games like Underwater include What Remains of Edith Finch, Firewatch, SOMA, Poppy Playtime, and Outer Wilds. We matched them by the tags players give Underwater on Steam (Adventure, Story Rich, Atmospheric, Survival Horror, and Mystery): closest matches first, and among equally close ones the better-known games.

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

Firewatch
Shared: Adventure · Story Rich · Atmospheric

SOMA
Shared: Atmospheric · Story Rich · Psychological Horror

Poppy Playtime
Shared: Survival Horror · Singleplayer · First-Person

Outer Wilds
Shared: Story Rich · Adventure · Mystery

Layers of Fear (2016)
Shared: Atmospheric · Psychological Horror · Story Rich

Amnesia: A Machine For Pigs
Shared: Story Rich · Atmospheric · Psychological Horror

Outlast
Shared: Atmospheric · Survival Horror · First-Person

Sally Face - Episode One
Shared: Story Rich · Psychological Horror · Adventure

Little Nightmares
Shared: Adventure · Atmospheric · Story Rich

Amnesia: The Dark Descent
Shared: Survival Horror · Atmospheric · Psychological Horror

Amnesia: Rebirth
Shared: Story Rich · Adventure · First-Person

Little Nightmares II
Shared: Adventure · Atmospheric · Story Rich

Bendy and the Ink Machine
Shared: First-Person · Survival Horror · Singleplayer

Penumbra Overture
Shared: Adventure · Survival Horror · Atmospheric

The Room Three
Shared: Adventure · Mystery · Atmospheric

Return of the Obra Dinn
Shared: Story Rich · Mystery · Atmospheric

INFRA
Shared: Atmospheric · Adventure · Story Rich

Resident Evil 7 Biohazard
Shared: Survival Horror · Atmospheric · First-Person

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

The Beast Inside
Shared: Adventure · Survival Horror · First-Person

SIGNALIS
Shared: Survival Horror · Atmospheric · Psychological Horror

The Room Two
Shared: Atmospheric · Mystery · Adventure

Call of the Sea
Shared: Adventure · Story Rich · First-Person