Games like Raging Titan
Games like Raging Titan include Taur, Planetary Annihilation: TITANS, DG2: Defense Grid 2, Starship Troopers: Terran Command, and Aliens: Dark Descent. We matched them by the tags players give Raging Titan on Steam (Tower Defense, Strategy, Real Time Tactics, Sci-fi, and Robots): closest matches first, and among equally close ones the better-known games.

Taur
Shared: Tower Defense · Strategy · Sci-fi

Planetary Annihilation: TITANS
Shared: Strategy · Real Time Tactics · Sci-fi

DG2: Defense Grid 2
Shared: Tower Defense · Strategy · Sci-fi

Starship Troopers: Terran Command
Shared: Strategy · Singleplayer · Tactical

Aliens: Dark Descent
Shared: Strategy · Real Time Tactics · Tactical

XCOM: Enemy Unknown
Shared: Strategy · Sci-fi · Tactical

Defense Grid: The Awakening
Shared: Tower Defense · Strategy · Sci-fi

Plants vs. Zombies GOTY Edition
Shared: Tower Defense · Strategy · Singleplayer

Creeper World 4
Shared: Tower Defense · Real Time Tactics · Strategy

Bloons TD 6
Shared: Tower Defense · Strategy · Singleplayer

Kingdom Rush - Tower Defense
Shared: Tower Defense · Strategy · Singleplayer

XCOM 2
Shared: Strategy · Tactical · Sci-fi

XCOM®: Chimera Squad
Shared: Strategy · Sci-fi · Singleplayer

Dune: Spice Wars
Shared: Sci-fi · Strategy · Singleplayer

Kingdom Rush Origins - Tower Defense
Shared: Tower Defense · Strategy · Singleplayer

Supreme Commander 2
Shared: Strategy · Sci-fi · Robots

Warhammer 40,000: Dawn of War - Anniversary Edition (Classic)
Shared: Strategy · Sci-fi · Singleplayer

Shadow Tactics: Blades of the Shogun
Shared: Strategy · Real Time Tactics · Tactical

BattleTech
Shared: Strategy · Sci-fi · Tactical

Outpost: Infinity Siege
Shared: Tower Defense · Robots · Sci-fi

Warpips
Shared: Tower Defense · Strategy · War

Infested Planet
Shared: Tower Defense · Strategy · Sci-fi

Warhammer 40,000: Dawn of War III
Shared: Strategy · Sci-fi · Singleplayer

Mechabellum
Shared: Strategy · Robots · Tactical