Games like Helium Rain
Games like Helium Rain include X4: Foundations, Elite Dangerous, X Rebirth, Kerbal Space Program, and Stellaris. We matched them by the tags players give Helium Rain on Steam (Simulation, Space Sim, Space, Strategy, and Indie): closest matches first, and among equally close ones the better-known games.

X4: Foundations
Shared: Simulation · Space · Space Sim

Elite Dangerous
Shared: Space Sim · Space · Simulation

X Rebirth
Shared: Simulation · Space · Space Sim

Kerbal Space Program
Shared: Simulation · Space · Space Sim

Stellaris
Shared: Space · Strategy · Simulation

Endless Sky
Shared: Space · Simulation · Free to Play

EVE Online
Shared: Space Sim · Simulation · Space

FTL: Faster Than Light
Shared: Space · Strategy · Indie

X3: Terran Conflict
Shared: Simulation · Space · Space Sim

Cosmoteer: Starship Architect & Commander
Shared: Space · Space Sim · Indie

Cosmonautica
Shared: Simulation · Space · Strategy

Starminer
Shared: Space Sim · Space · Economy

Between the Stars
Shared: Space · Simulation · Action

House of the Dying Sun
Shared: Simulation · Space · Space Sim

Game Dev Tycoon
Shared: Simulation · Strategy · Indie

SPORE™ Galactic Adventures
Shared: Simulation · Space · Action

Rebel Galaxy
Shared: Space · Space Sim · Simulation

Deliver Us The Moon
Shared: Space · Indie · Action

Avorion
Shared: Space Sim · Space · Exploration

Sins of a Solar Empire®: Rebellion
Shared: Simulation · Space · Strategy

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

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

Hardspace: Shipbreaker
Shared: Simulation · Space · Space Sim

Starpoint Gemini 2
Shared: Simulation · Space · Space Sim