Games like X3: Reunion
Games like X3: Reunion include X4: Foundations, Elite Dangerous, X Rebirth, Stellaris, and X3: Terran Conflict. We matched them by the tags players give X3: Reunion on Steam (Space, Simulation, Strategy, Space Sim, and Sci-fi): closest matches first, and among equally close ones the better-known games.
X4: Foundations
Shared: Space · Simulation · Space Sim
Elite Dangerous
Shared: Space · Space Sim · Simulation
X Rebirth
Shared: Space · Simulation · Sci-fi
Stellaris
Shared: Space · Strategy · Sci-fi
X3: Terran Conflict
Shared: Space · Simulation · Strategy
Kerbal Space Program
Shared: Space · Simulation · Sandbox
No Man's Sky
Shared: Space · Sci-fi · Open World
EVE Online
Shared: Space Sim · Space · Simulation
Hardspace: Shipbreaker
Shared: Space · Simulation · Sci-fi
Avorion
Shared: Space · Space Sim · Sandbox
Starpoint Gemini Warlords
Shared: Space · Strategy · Simulation
Dyson Sphere Program
Shared: Space · Simulation · Sci-fi
Starminer
Shared: Space · Space Sim · Sandbox
SPORE™ Galactic Adventures
Shared: Simulation · Space · Strategy
Endless Sky
Shared: Space · Simulation · Sci-fi
SPORE™
Shared: Simulation · Space · Sandbox
Space Engineers
Shared: Space · Simulation · Sandbox
Rebel Galaxy
Shared: Space · Sci-fi · Open World
SpaceEngine
Shared: Space · Sci-fi · Space Sim
Jurassic World Evolution
Shared: Simulation · Strategy · Sandbox
X2: The Threat
Shared: Space · Simulation · Strategy
Empyrion - Galactic Survival
Shared: Simulation · Space · Space Sim
Kerbal Space Program 2
Shared: Space · Sandbox · Simulation
Starpoint Gemini 2
Shared: Space · Simulation · Sci-fi