Games like Battlements
Games like Battlements include Bloons TD 6, Counter-Strike 2, Ninja Kiwi Archive, Tom Clancy's Rainbow Six Siege, and THE FINALS. We matched them by the tags players give Battlements on Steam (Tower Defense, Shooter, Pixel Graphics, Destruction, and PvE): closest matches first, and among equally close ones the better-known games.

Bloons TD 6
Shared: Tower Defense · Strategy · Family Friendly

Counter-Strike 2
Shared: Shooter · Multiplayer · PvP

Ninja Kiwi Archive
Shared: Tower Defense · Arcade · Strategy

Tom Clancy's Rainbow Six Siege
Shared: Shooter · PvP · Multiplayer

THE FINALS
Shared: Destruction · Shooter · PvP

Broforce
Shared: Pixel Graphics · Shooter · Action

Plants vs. Zombies: Battle for Neighborville™
Shared: Shooter · Tower Defense · PvE

PUBG: BATTLEGROUNDS
Shared: Shooter · PvP · Multiplayer

Pixel Gun 3D: PC Edition
Shared: Pixel Graphics · Shooter · PvP

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

ARC Raiders
Shared: PvE · Shooter · PvP

Squad
Shared: Shooter · PvE · PvP

BattleBit Remastered
Shared: Shooter · Destruction · PvP

HELLDIVERS™ 2
Shared: Shooter · PvE · Multiplayer

Planes, Bullets and Vodka
Shared: Shooter · Arcade · Pixel Graphics

UFO 50
Shared: Pixel Graphics · Arcade · Indie

Dungeon Warfare
Shared: Tower Defense · Pixel Graphics · Top-Down

Legion TD 2 - Multiplayer Tower Defense
Shared: Tower Defense · PvP · PvE

Cluckmech Oasis
Shared: Tower Defense · Pixel Graphics · Shooter

Bloons TD 5
Shared: Tower Defense · Strategy · Family Friendly

ShellShock Live
Shared: Shooter · Strategy · Multiplayer

Baba Is You
Shared: Pixel Graphics · Puzzle · Indie

The Escapists
Shared: Pixel Graphics · Strategy · Puzzle

Duck Game
Shared: Pixel Graphics · Shooter · Multiplayer