Games like The Astronomy Game
Games like The Astronomy Game include Kerbal Space Program, Elite Dangerous, X4: Foundations, No Man's Sky, and Cosmoteer: Starship Architect & Commander. We matched them by the tags players give The Astronomy Game on Steam (Space, Trivia, Text-Based, Simulation, and Logic): closest matches first, and among equally close ones the better-known games.

Kerbal Space Program
Shared: Space · Simulation · Space Sim

Elite Dangerous
Shared: Space · Space Sim · Simulation

X4: Foundations
Shared: Space · Simulation · Space Sim

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

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

Stellaris
Shared: Space · Simulation · Exploration

Spaceflight Simulator
Shared: Space · Simulation · Space Sim

Kerbal Space Program 2
Shared: Space · Simulation · Exploration

EVE Online
Shared: Space · Space Sim · Simulation

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

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

Outer Wilds
Shared: Space · Exploration · Atmospheric

Universe Sandbox
Shared: Space · Simulation · Space Sim

X Rebirth
Shared: Space · Simulation · Space Sim

Deliver Us The Moon
Shared: Space · Adventure · Indie

Endless Sky
Shared: Space · Simulation · Sci-fi

Rebel Galaxy
Shared: Space · Simulation · Space Sim

Starfield
Shared: Space · Exploration · Sci-fi

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

Papers, Please
Shared: Simulation · Point & Click · Indie

SPORE™ Galactic Adventures
Shared: Space · Simulation · Exploration

Nimbatus - The Space Drone Constructor
Shared: Space · Space Sim · Exploration

Exo One
Shared: Space · Atmospheric · Exploration

SPORE™
Shared: Space · Simulation · Exploration