Games like Fortified Space
Games like Fortified Space include Elite Dangerous, Dyson Sphere Program, DG2: Defense Grid 2, FTL: Faster Than Light, and Taur. We matched them by the tags players give Fortified Space on Steam (Space Sim, Tower Defense, Vehicular Combat, Sci-fi, and Base Building): closest matches first, and among equally close ones the better-known games.
Elite Dangerous
Shared: Space Sim · Sci-fi · Space
Dyson Sphere Program
Shared: Base Building · Space · Sci-fi
DG2: Defense Grid 2
Shared: Tower Defense · Sci-fi · Base Building
FTL: Faster Than Light
Shared: Sci-fi · Space · Strategy
Taur
Shared: Tower Defense · Base Building · Sci-fi
X Rebirth
Shared: Space Sim · Sci-fi · Space
X4: Foundations
Shared: Space Sim · Space · Sci-fi
War Thunder
Shared: Vehicular Combat · Action · Simulation
Dome Keeper
Shared: Sci-fi · Tower Defense · Action
Starpoint Gemini Warlords
Shared: Space Sim · Sci-fi · Space
Creeper World 3: Arc Eternal
Shared: Tower Defense · Sci-fi · Base Building
Space Haven
Shared: Base Building · Space · Sci-fi
Cosmoteer: Starship Architect & Commander
Shared: Sci-fi · Space Sim · Space
V: Rings of Saturn
Shared: Sci-fi · Space Sim · Space
Hardspace: Shipbreaker
Shared: Sci-fi · Space · Space Sim
STAR WARS™ Empire at War - Gold Pack
Shared: Sci-fi · Space · Strategy
Halo Wars: Definitive Edition
Shared: Base Building · Sci-fi · Strategy
Aliens: Dark Descent
Shared: Sci-fi · Action · Tactical
Warhammer 40,000: Dawn of War III
Shared: Sci-fi · Base Building · Action
Rise to Ruins
Shared: Tower Defense · Base Building · Pixel Graphics
Until We Die
Shared: Tower Defense · Base Building · Pixel Graphics
X-Morph: Defense
Shared: Tower Defense · Sci-fi · Action
Cluckmech Oasis
Shared: Tower Defense · Top-Down Shooter · Pixel Graphics
House of the Dying Sun
Shared: Space Sim · Action · Sci-fi