Games like The Unknown
Games like The Unknown include Firewatch, There Is No Game: Wrong Dimension, DAVE THE DIVER, Slime Rancher, and The Stanley Parable. We matched them by the tags players give The Unknown on Steam (Adventure, Casual, Point & Click, Walking Simulator, and Mystery Dungeon): closest matches first, and among equally close ones the better-known games.

Firewatch
Shared: Adventure · Walking Simulator · First-Person

There Is No Game: Wrong Dimension
Shared: Adventure · Point & Click · Indie

DAVE THE DIVER
Shared: Casual · Adventure · Pixel Graphics

Slime Rancher
Shared: Adventure · Exploration · First-Person

The Stanley Parable
Shared: Walking Simulator · Indie · Adventure

The Invincible
Shared: Adventure · Walking Simulator · Futuristic

A Short Hike
Shared: Adventure · Exploration · Indie

Tacoma
Shared: Adventure · Walking Simulator · Indie

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

What Remains of Edith Finch
Shared: Walking Simulator · Adventure · Exploration

That's not my Neighbor
Shared: Adventure · Casual · Point & Click

Journey
Shared: Adventure · Indie · Exploration

Outer Wilds
Shared: Adventure · Exploration · Space

Obduction
Shared: Adventure · Indie · Exploration

Valley
Shared: Adventure · Exploration · First-Person

Gone Home
Shared: Walking Simulator · Indie · Exploration

The Room
Shared: Point & Click · Adventure · Indie

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

The Witness
Shared: Exploration · First-Person · Indie

Proteus
Shared: Walking Simulator · Casual · Exploration

Jazzpunk: Director's Cut
Shared: Adventure · Indie · Exploration

Cradle
Shared: Adventure · Indie · Exploration

Starbound
Shared: Adventure · Pixel Graphics · Casual

FEZ
Shared: Indie · Adventure · Casual