Games like Colony Siege
Games like Colony Siege include Bloons TD 6, The Riftbreaker, Mindustry, Warhammer 40,000: Dawn of War - Definitive Edition, and Dota 2. We matched them by the tags players give Colony Siege on Steam (Strategy, Simulation, Tower Defense, Sci-fi, and RTS): closest matches first, and among equally close ones the better-known games.
Bloons TD 6
Shared: Strategy · Tower Defense · Co-op
The Riftbreaker
Shared: Tower Defense · Online Co-Op · Base Building
Mindustry
Shared: Tower Defense · Strategy · RTS
Warhammer 40,000: Dawn of War - Definitive Edition
Shared: Strategy · RTS · Sci-fi
Dota 2
Shared: Strategy · Multiplayer · Online Co-Op
Halo Wars: Definitive Edition
Shared: Strategy · RTS · Sci-fi
Supreme Commander: Forged Alliance
Shared: Strategy · Sci-fi · RTS
Company of Heroes 2
Shared: Strategy · RTS · Multiplayer
Creeper World 3: Arc Eternal
Shared: Strategy · Tower Defense · RTS
Warhammer 40,000: Dawn of War II - Anniversary Edition (Classic)
Shared: Strategy · Sci-fi · RTS
Command & Conquer™ Red Alert™ 3
Shared: Strategy · RTS · Base Building
Planetary Annihilation: TITANS
Shared: Strategy · RTS · Sci-fi
Sanctum 2
Shared: Tower Defense · Strategy · Co-op
Legion TD 2 - Multiplayer Tower Defense
Shared: Tower Defense · Strategy · Multiplayer
7 Days to Die
Shared: Survival · Multiplayer · Online Co-Op
Don't Starve Together
Shared: Co-op · Survival · Multiplayer
Barotrauma
Shared: Co-op · Simulation · Multiplayer
Raft
Shared: Co-op · Multiplayer · Survival
Dungeons 3
Shared: Strategy · Simulation · RTS
RimWorld
Shared: Strategy · Simulation · Base Building
Warhammer 40,000: Dawn of War III
Shared: Strategy · Sci-fi · RTS
Supreme Commander 2
Shared: Strategy · Sci-fi · RTS
Abiotic Factor
Shared: Online Co-Op · Sci-fi · Survival
Age of Empires II (Retired)
Shared: Strategy · RTS · Multiplayer