Games like Galactic Siege
Games like Galactic Siege include The Alters, Oxygen Not Included, RimWorld, Bloons TD 6, and Orcs Must Die! 3. We matched them by the tags players give Galactic Siege on Steam (Strategy, Tower Defense, PvE, 3D, and Magic): closest matches first, and among equally close ones the better-known games.
The Alters
Shared: Strategy · Management · Survival
Oxygen Not Included
Shared: Survival · Management · Strategy
RimWorld
Shared: Strategy · Management · Survival
Bloons TD 6
Shared: Strategy · Tower Defense · 3D
Orcs Must Die! 3
Shared: Tower Defense · Strategy · PvE
Dyson Sphere Program
Shared: Space · Sci-fi · Strategy
Legion TD 2 - Multiplayer Tower Defense
Shared: Tower Defense · Strategy · PvE
Stellaris
Shared: Strategy · Space · Sci-fi
Sanctum 2
Shared: Tower Defense · Strategy · Sci-fi
FTL: Faster Than Light
Shared: Strategy · Space · Sci-fi
Age of Darkness: Final Stand
Shared: Tower Defense · Strategy · PvE
Defense Grid: The Awakening
Shared: Strategy · Tower Defense · Sci-fi
Space Haven
Shared: Strategy · Management · Survival
Thronefall
Shared: Strategy · Tower Defense · 3D
Outpost: Infinity Siege
Shared: Tower Defense · 3D · Strategy
Taur
Shared: Strategy · Tower Defense · Sci-fi
They Are Billions
Shared: Strategy · Tower Defense · Survival
Creeper World 3: Arc Eternal
Shared: Strategy · Tower Defense · Sci-fi
Space Run
Shared: Strategy · Tower Defense · Space
Warhammer 40,000: Space Marine 2
Shared: PvE · Action · Sci-fi
Dungeon Defenders
Shared: Tower Defense · Strategy · Survival
Mindustry
Shared: Tower Defense · Strategy · Resource Management
Spacebase DF-9
Shared: Strategy · Space · Sci-fi
Planetbase
Shared: Strategy · Space · Survival