Games like G Prime
Games like G Prime include Kerbal Space Program, Space Engineers, Hardspace: Shipbreaker, Poly Bridge, and Papers, Please. We matched them by the tags players give G Prime on Steam (Indie, Simulation, Space, Puzzle, and Physics): closest matches first, and among equally close ones the better-known games.

Kerbal Space Program
Shared: Simulation · Space · Physics

Space Engineers
Shared: Space · Simulation · Physics

Hardspace: Shipbreaker
Shared: Space · Simulation · Physics

Poly Bridge
Shared: Simulation · Puzzle · Physics

Papers, Please
Shared: Indie · Simulation · Puzzle

Heavenly Bodies
Shared: Space · Physics · Simulation

Besiege
Shared: Simulation · Physics · Puzzle

Opus Magnum
Shared: Indie · Puzzle · Simulation

Empyrion - Galactic Survival
Shared: Simulation · Space · Indie

Poly Bridge 2
Shared: Simulation · Puzzle · Physics

Surgeon Simulator
Shared: Simulation · Indie · Physics

Universe Sandbox
Shared: Simulation · Space · Physics

Universe Sandbox
Shared: Simulation · Space · Indie

Totally Accurate Battle Simulator
Shared: Simulation · Indie · Physics

Cyber Manhunt
Shared: Simulation · Indie · Puzzle

Viscera Cleanup Detail
Shared: Simulation · Indie · Physics

Deliver Us The Moon
Shared: Indie · Space · Puzzle

Bridge Constructor Portal
Shared: Simulation · Puzzle · Physics

Mountain
Shared: Indie · Simulation · Space

Goat Simulator
Shared: Simulation · Indie · Physics

Defy Gravity Extended
Shared: Indie · Puzzle · Space

Outer Wilds
Shared: Space · Puzzle · Indie

Kerbal Space Program 2
Shared: Space · Simulation · Physics

Zup! S
Shared: Indie · Puzzle · Physics