Games like X3: Terran Conflict Bonus Package
Games like X3: Terran Conflict Bonus Package include Elite Dangerous, X4: Foundations, Stellaris, Kerbal Space Program, and X Rebirth. We matched them by the tags players give X3: Terran Conflict Bonus Package on Steam (Strategy, Space Sim, Simulation, Space, and Sci-fi): closest matches first, and among equally close ones the better-known games.

Elite Dangerous
Shared: Space Sim · Space · Simulation

X4: Foundations
Shared: Simulation · Space · Space Sim

Stellaris
Shared: Strategy · Space · Sci-fi

Kerbal Space Program
Shared: Simulation · Space · Space Sim

X Rebirth
Shared: Simulation · Space · Space Sim

EVE Online
Shared: Space Sim · Exploration · Space

SPORE™ Galactic Adventures
Shared: Simulation · Space · Action

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

X3: Terran Conflict
Shared: Simulation · Space · Strategy

SPORE™
Shared: Simulation · Sandbox · Space

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

Avorion
Shared: Space Sim · Exploration · Sandbox

Kerbal Space Program 2
Shared: Space · Exploration · Sandbox

Universe Sandbox
Shared: Simulation · Space Sim · Space

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

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

Starpoint Gemini Warlords
Shared: Strategy · Space · Simulation

Spaceflight Simulator
Shared: Space Sim · Simulation · Space

FTL: Faster Than Light
Shared: Strategy · Space · Sci-fi

Between the Stars
Shared: Space · Simulation · Strategy

Cosmoteer: Starship Architect & Commander
Shared: Sci-fi · Space · Strategy

Space Haven
Shared: Strategy · Space · Simulation

Starminer
Shared: Space Sim · Space · Sandbox

The Last Starship
Shared: Simulation · Strategy · Space