Games like Rocket Science
Games like Rocket Science include Kerbal Space Program, Kerbal Space Program 2, Universe Sandbox, Space Engineers, and X4: Foundations. We matched them by the tags players give Rocket Science on Steam (Space, Exploration, Sandbox, Building, and Physics): closest matches first, and among equally close ones the better-known games.

Kerbal Space Program
Shared: Space · Sandbox · Physics

Kerbal Space Program 2
Shared: Space · Exploration · Sandbox

Universe Sandbox
Shared: Space · Sandbox · Simulation

Space Engineers
Shared: Space · Sandbox · Building

X4: Foundations
Shared: Space · Exploration · Sandbox

Spaceflight Simulator
Shared: Space · Sandbox · Exploration

Avorion
Shared: Exploration · Sandbox · Space

Space Engineers 2
Shared: Space · Sandbox · Building

Empyrion - Galactic Survival
Shared: Space · Simulation · Building

SpaceEngine
Shared: Space · Sandbox · Space Sim

Aviassembly
Shared: Building · Sandbox · Physics

Elite Dangerous
Shared: Space · Exploration · Space Sim

No Man's Sky
Shared: Space · Exploration · Sandbox

SPORE™
Shared: Sandbox · Exploration · Space

Dyson Sphere Program
Shared: Space · Building · Sandbox

Hardspace: Shipbreaker
Shared: Space · Physics · Sandbox

Juno: New Origins
Shared: Building · Science · Space Sim

Stormworks: Build and Rescue
Shared: Sandbox · Building · Physics

Stellaris
Shared: Space · Exploration · Sandbox

Garry's Mod
Shared: Sandbox · Building · Physics

BeamNG.drive
Shared: Physics · Simulation · Sandbox

EVE Online
Shared: Exploration · Space · Space Sim

Take On Mars
Shared: Space · Exploration · Simulation

Solar Expanse - Space Exploration Manager
Shared: Space · Sandbox · Simulation

