Games like Gravity Knight
Games like Gravity Knight include Portal, Portal 2, The Last Campfire, Trine 2: Complete Story, and Poppy Playtime. We matched them by the tags players give Gravity Knight on Steam (Free to Play, Puzzle, Puzzle Platformer, Third Person, and Fantasy): closest matches first, and among equally close ones the better-known games.

Portal
Shared: Puzzle · Puzzle Platformer · 3D Platformer

Portal 2
Shared: Puzzle · Puzzle Platformer · Singleplayer

The Last Campfire
Shared: Puzzle · Singleplayer · Fantasy

Trine 2: Complete Story
Shared: Puzzle Platformer · Puzzle · Fantasy

Poppy Playtime
Shared: Free to Play · Puzzle · Singleplayer

LIMBO
Shared: Puzzle Platformer · Puzzle · Indie

Human Fall Flat
Shared: Puzzle · Puzzle Platformer · Physics

Viewfinder
Shared: Puzzle · Puzzle Platformer · Singleplayer

Trine 3: The Artifacts of Power
Shared: Puzzle Platformer · 3D Platformer · Fantasy

Where Winds Meet
Shared: Free to Play · Singleplayer · Fantasy

Idle Champions of the Forgotten Realms
Shared: Free to Play · Fantasy · Singleplayer

Papo & Yo
Shared: Puzzle Platformer · Puzzle · 3D Platformer

Zup!
Shared: Puzzle · Puzzle Platformer · Indie

Supraland
Shared: Puzzle Platformer · Puzzle · Physics

Monument Valley
Shared: Puzzle · Singleplayer · Casual

Zup! F
Shared: Puzzle · Puzzle Platformer · Indie

Zup! 3
Shared: Puzzle · Puzzle Platformer · Indie

Defy Gravity Extended
Shared: Puzzle Platformer · Puzzle · Indie

Zup! 2
Shared: Puzzle · Puzzle Platformer · Indie

Zup! X
Shared: Puzzle · Puzzle Platformer · Indie

Quantum Conundrum
Shared: Puzzle · Puzzle Platformer · 3D Platformer

Zup! S
Shared: Puzzle · Physics · Indie

Guild Wars 2®
Shared: Free to Play · Fantasy · Third Person

Tiny and Big: Grandpas Leftovers
Shared: Puzzle · Physics · 3D Platformer