Games like Rocketeer
Games like Rocketeer include SpaceEngine, Kerbal Space Program, Goat Simulator, Universe Sandbox, and Hardspace: Shipbreaker. We matched them by the tags players give Rocketeer on Steam (Casual, Simulation, Arcade, Space Sim, and Side Scroller): closest matches first, and among equally close ones the better-known games.

SpaceEngine
Shared: Casual · Space Sim · 3D

Kerbal Space Program
Shared: Simulation · Space Sim · Space

Goat Simulator
Shared: Simulation · Casual · Physics

Universe Sandbox
Shared: Simulation · Space Sim · Space

Hardspace: Shipbreaker
Shared: Simulation · Sci-fi · Space Sim

X4: Foundations
Shared: Simulation · Space Sim · Space

Elite Dangerous
Shared: Space Sim · Simulation · Sci-fi

Avorion
Shared: Space Sim · 3D · Simulation

Starpoint Gemini 2
Shared: Simulation · Space Sim · Sci-fi

ACE COMBAT™ 7: SKIES UNKNOWN
Shared: Arcade · 3D · Flight

PowerWash Simulator
Shared: Casual · Simulation · 3D

Drift86
Shared: Casual · Arcade · Simulation

Universe Sandbox
Shared: Simulation · Casual · Space

Mountain
Shared: Simulation · Casual · Indie

Slackers - Carts of Glory
Shared: Simulation · Casual · Third Person

1000 days to escape
Shared: Casual · Arcade · Simulation

Dyson Sphere Program
Shared: Simulation · Space · Sci-fi

That's not my Neighbor
Shared: Casual · Simulation · Arcade

SpaceBourne 2
Shared: Space Sim · 3D · Third Person

Internet Cafe Simulator 2
Shared: Simulation · 3D · Arcade

The Coin Game
Shared: Arcade · Casual · Simulation

Placid Plastic Duck Simulator
Shared: Casual · Simulation · 3D

Empyrion - Galactic Survival
Shared: Simulation · Space Sim · Space

Coin Pusher Casino
Shared: Arcade · Simulation · Casual