Games like Operation Defensive!
Games like Operation Defensive! include Kingdom Rush - Tower Defense, Plants vs. Zombies GOTY Edition, Kingdom Rush Frontiers - Tower Defense, Bloons TD 6, and Kingdom Rush Origins - Tower Defense. We matched them by the tags players give Operation Defensive! on Steam (Casual, Tower Defense, 2D, Top-Down, and Fantasy): closest matches first, and among equally close ones the better-known games.

Kingdom Rush - Tower Defense
Shared: Tower Defense · 2D · Casual

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

Kingdom Rush Frontiers - Tower Defense
Shared: Tower Defense · 2D · Singleplayer

Bloons TD 6
Shared: Tower Defense · Casual · Singleplayer

Kingdom Rush Origins - Tower Defense
Shared: Tower Defense · 2D · Casual

GemCraft - Chasing Shadows
Shared: Tower Defense · Top-Down · Singleplayer

Idle Champions of the Forgotten Realms
Shared: Fantasy · Free to Play · Singleplayer

Kingdom Rush 5: Alliance TD
Shared: Tower Defense · 2D · Singleplayer

Where Winds Meet
Shared: Free to Play · Singleplayer · Casual

A Dance of Fire and Ice
Shared: 2D · Singleplayer · Indie

Melvor Idle
Shared: Casual · 2D · Singleplayer

Emily is Away
Shared: Free to Play · Singleplayer · Casual

Dungeon Warfare
Shared: Tower Defense · 2D · Indie

Zup! S
Shared: Casual · 2D · Indie

Vampire Survivors
Shared: 2D · Casual · Singleplayer

Game Dev Tycoon
Shared: Casual · 2D · Indie

Rock 'N' Roll Defense
Shared: Tower Defense · Casual · 2D

Circle Empires
Shared: Casual · Fantasy · Indie

Minimalist Tower Defense
Shared: Tower Defense · Top-Down · 2D

Relic Guardian - Tower Defense
Shared: Tower Defense · 2D · Casual

Brawlhalla
Shared: Casual · Free to Play · Fantasy

Bloons TD 5
Shared: Tower Defense · Casual · 2D

Razortron 2000
Shared: Casual · Top-Down · 2D

Defend Your Life: TD
Shared: Casual · Tower Defense · 2D

