Games like Deep Space: Unknown Universe
Games like Deep Space: Unknown Universe include Outer Wilds, Starfield, No Man's Sky, The Talos Principle, and Deliver Us The Moon. We matched them by the tags players give Deep Space: Unknown Universe on Steam (Space, Puzzle, Atmospheric, Sci-fi, and First-Person): closest matches first, and among equally close ones the better-known games.

Outer Wilds
Shared: Space · Atmospheric · Puzzle

Starfield
Shared: Space · Sci-fi · First-Person

No Man's Sky
Shared: Space · Sci-fi · Exploration

The Talos Principle
Shared: Puzzle · Sci-fi · First-Person

Deliver Us The Moon
Shared: Space · Sci-fi · Atmospheric

The Witness
Shared: Puzzle · First-Person · Atmospheric

The Turing Test
Shared: Puzzle · Sci-fi · Space

Firewatch
Shared: Atmospheric · First-Person · Walking Simulator

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

ROUTINE
Shared: Sci-fi · Atmospheric · Puzzle

Observation
Shared: Space · Sci-fi · Atmospheric

Fallout 4
Shared: Atmospheric · First-Person · RPG

COCOON
Shared: Puzzle · Atmospheric · Indie

The Swapper
Shared: Puzzle · Space · Atmospheric

Prey
Shared: Space · Sci-fi · Atmospheric

LOCKDOWN Protocol
Shared: Space · Dialogue Heavy · First-Person

Stray
Shared: Atmospheric · Puzzle · Adventure

Cradle
Shared: Atmospheric · Sci-fi · Puzzle

Tacoma
Shared: Space · Sci-fi · Walking Simulator

INFRA
Shared: Puzzle · Atmospheric · First-Person

SOMA
Shared: Atmospheric · Sci-fi · First-Person

Antichamber
Shared: Puzzle · First-Person · Indie

Exo One
Shared: Space · Atmospheric · Exploration

Riven
Shared: Puzzle · First-Person · Atmospheric