Games like Zompioland
Games like Zompioland include Bloons TD 6, DG2: Defense Grid 2, Aliens: Dark Descent, Element TD 2 - Tower Defense, and Plants vs. Zombies GOTY Edition. We matched them by the tags players give Zompioland on Steam (Strategy, Tower Defense, Real Time Tactics, 3D, and Sci-fi): closest matches first, and among equally close ones the better-known games.

Bloons TD 6
Shared: Strategy · Tower Defense · 3D

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

Aliens: Dark Descent
Shared: Strategy · Real Time Tactics · Sci-fi

Element TD 2 - Tower Defense
Shared: Tower Defense · Real Time Tactics · Strategy

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

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

Outpost: Infinity Siege
Shared: Tower Defense · 3D · Sci-fi

Thronefall
Shared: Strategy · Tower Defense · 3D

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

Taur
Shared: Strategy · Tower Defense · Sci-fi

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

Battlefleet Gothic: Armada 2
Shared: Strategy · Real Time Tactics · Sci-fi

No Creeps Were Harmed TD
Shared: Strategy · Tower Defense · 3D

Artisan TD
Shared: Strategy · Tower Defense · Real Time Tactics

Dota 2
Shared: Strategy · Team-Based · Tower Defense

Sanctum 2
Shared: Tower Defense · Strategy · Sci-fi

Rogue Tower
Shared: Strategy · Tower Defense · 3D

Creeper World 3: Arc Eternal
Shared: Strategy · Tower Defense · Sci-fi

Starship Troopers: Terran Command
Shared: Strategy · Sci-fi · Singleplayer

Warhammer 40,000: Battlesector
Shared: Strategy · 3D · Sci-fi

Orcs Must Die! 3
Shared: Tower Defense · Strategy · 3D

Minimalist Tower Defense
Shared: Strategy · Tower Defense · Real Time Tactics

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