Games like Bloons TD 6
Games like Bloons TD 6 include Bloons TD 5, Plants vs. Zombies GOTY Edition, Dungeon Defenders, Dota 2, and Dungeon Defenders: Awakened. We matched them by the tags players give Bloons TD 6 on Steam (Tower Defense, Strategy, Multiplayer, Singleplayer, and Online Co-Op): closest matches first, and among equally close ones the better-known games.

Bloons TD 5
Shared: Tower Defense · Strategy · Co-op

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

Dungeon Defenders
Shared: Tower Defense · Multiplayer · Strategy

Dota 2
Shared: Multiplayer · Strategy · Online Co-Op

Dungeon Defenders: Awakened
Shared: Multiplayer · Tower Defense · Singleplayer

Ninja Kiwi Archive
Shared: Strategy · Tower Defense · Casual

UNO
Shared: Multiplayer · Strategy · Family Friendly

The Escapists 2
Shared: Strategy · Multiplayer · Online Co-Op

Among Us
Shared: Multiplayer · Online Co-Op · Co-op

Garry's Mod
Shared: Multiplayer · Singleplayer · Sandbox

Orcs Must Die! 2
Shared: Tower Defense · Strategy · Co-op

Overcooked! 2
Shared: Multiplayer · Online Co-Op · Co-op

Don't Starve Together
Shared: Multiplayer · Co-op · Online Co-Op

Orcs Must Die! 3
Shared: Tower Defense · Strategy · Co-op

PowerWash Simulator
Shared: Multiplayer · Casual · Co-op

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

Legion TD 2 - Multiplayer Tower Defense
Shared: Tower Defense · Multiplayer · Strategy

Liars Bar
Shared: Multiplayer · Online Co-Op · Casual

Golf With Your Friends
Shared: Multiplayer · Casual · Singleplayer

Castle Crashers®
Shared: Online Co-Op · Co-op · Multiplayer

Mindustry
Shared: Tower Defense · Strategy · Multiplayer

The Riftbreaker
Shared: Tower Defense · Multiplayer · Online Co-Op

Command & Conquer™ Red Alert™ 3
Shared: Strategy · Multiplayer · Family Friendly

Sanctum 2
Shared: Tower Defense · Strategy · Co-op