Games like Cosmonautica
Games like Cosmonautica include X4: Foundations, Stellaris, X Rebirth, Elite Dangerous, and FTL: Faster Than Light. We matched them by the tags players give Cosmonautica on Steam (Trading, Space, Simulation, Strategy, and Economy): closest matches first, and among equally close ones the better-known games.

X4: Foundations
Shared: Space · Simulation · Strategy

Stellaris
Shared: Space · Strategy · Sci-fi

X Rebirth
Shared: Space · Simulation · Sci-fi

Elite Dangerous
Shared: Space · Simulation · Sci-fi

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

Kerbal Space Program
Shared: Space · Simulation · Space Sim

EVE Online
Shared: Space · Trading · Simulation

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

Game Dev Tycoon
Shared: Simulation · Strategy · Management

X3: Terran Conflict
Shared: Space · Simulation · Strategy

Endless Sky
Shared: Space · Simulation · Sci-fi

Supermarket Simulator
Shared: Simulation · Trading · Economy

Cities: Skylines
Shared: Simulation · Strategy · Management

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

Planet Coaster
Shared: Simulation · Management · Strategy

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

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

Jurassic World Evolution
Shared: Simulation · Strategy · Management

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

Starminer
Shared: Space · Trading · Economy

Tropico 6
Shared: Simulation · Strategy · Economy

SPORE™ Galactic Adventures
Shared: Simulation · Space · Adventure

Rebel Galaxy
Shared: Space · Sci-fi · Simulation

Anno 2205™
Shared: Simulation · Strategy · Sci-fi