Single-player games like Colony Siege
Below are 11 single-player Steam games similar to Colony Siege, ranked by player overlap. Every pick carries Steam's Single-player category, so multiplayer-only titles or always-online games don't sneak in. imho.run pulls the category data from Steam directly — Single-player here matches what the store labels.
Want the full alternatives list (paid + free + Steam Deck + cheaper picks)? See the parent games like Colony Siege page.
Ranked picks
- 1
Axon TD: Uprising - Tower Defense
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Axon TD lets you expand the map boundaries themselves. A huge arsenal of towers and a wide variety of enemies clash in a battlefield that grows to your whims. Engage in single, cooperative, and roguelite gameplay.
- 2
Siege of Centauri
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Defend against thousands of enemies in this explosive tower defense game. Deploy upgradable towers and unleash powerful orbital abilities as you try to protect Earth's first colony world from destruction.
- 3
AI War 2
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy and Simulation with Colony Siege.
The most devious and acclaimed artificial intelligence in strategy gaming is better than ever. A grand strategy/RTS hybrid that reverses many conventions of both genres. Take territory without attracting attention, build your empire with care, and adapt to an ever-evolving galactic battleground.
- 4
MarZ: Tactical Base Defense
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Build your defense base to fight back the undead hordes of Mars and secure the future of the red planet. MarZ is a game of strategy and tactical defense where you must carefully manage your crew and resources as you try to uncover the terrible secrets of the undead.
- 5
The Riftbreaker
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
The Riftbreaker is a solo or Co-op base-building, survival game with Action-RPG elements for up to 4 players. Hack & slash countless hordes of enemies. Build up your base, craft powerful weapons and research new inventions to survive.
- 6
Taur
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Taur is an action-strategy sci-fi game. Control the Prime Cannon and unlock all of its powerful weapons and abilities. Build turrets, droids, aircraft and more as you fight to protect the homeworld of the Tauron droids against a relentless invasion. Will your Taur stand against the Imperion warmachine?
- 7
Deep Among the Swarm
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Deep Among the Swarm is a challenging survival RTS roguelite about surviving against thousands of enemies. Drill ever deeper underground while fighting the endless onslaught of the Swarm. Can you save humanity?
- 8
Conan Unconquered
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
From the Command & Conquer veterans at Petroglyph comes the first ever survival RTS set in the savage world of Conan the Barbarian. Play solo or team up in multiplayer in Conan Unconquered’s action-packed co-op Mode where you build a shared stronghold and fend off the hordes together.
- 9
Grey Goo
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Fight for control of a frontier world. Gather resources, build your base, and command your forces in battle. Survive long enough to unleash your ultimate weapon - THE EPIC.
- 10
X-Morph: Defense
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Unique fusion of a top-down shooter and tower defense strategy. You are the invader! Use destructive weapons or lead your enemies into a maze of towers. Strategize in the build mode by carefully selecting various types of alien towers or throw yourself right into the heat of the battle.
- 11
GRID DEFENSE: GRID WAR
Single-player alternative to Colony Siege — playable solo, no multiplayer required. Shares Strategy with Colony Siege.
Build towers, unleash ultimates and command six heroes in sci-fi tower defense. Play all 100 Scenario stages free. Try one-minute highlights of Basic and GRID COMMAND before purchase, then take your aerial fleet into GRID COMMAND's survival battles.