Games like Cosmic Swarm
Games like Cosmic Swarm include HELLDIVERS™ 2, STAR WARS™ Battlefront™ II, OPERATOR, Ready or Not, and Incursion Red River. We matched them by the tags players give Cosmic Swarm on Steam (Shoot 'Em Up, Action, PvE, Shooter, and 3D): closest matches first, and among equally close ones the better-known games.

HELLDIVERS™ 2
Shared: PvE · Action · Shooter

STAR WARS™ Battlefront™ II
Shared: Shooter · Action · Space

OPERATOR
Shared: Shooter · Action · PvE

Ready or Not
Shared: Shooter · Tactical · Action

Incursion Red River
Shared: PvE · Action · Gun Customization

Starship Troopers: Extermination
Shared: Action · PvE · Sci-fi

Soda Crisis
Shared: Action · Shoot 'Em Up · Shooter

EARTH DEFENSE FORCE 6
Shared: Action · Shooter · PvE

Warhammer 40,000: Space Marine 2
Shared: Action · PvE · Sci-fi

The Callisto Protocol™
Shared: Shooter · PvE · Sci-fi

STAR WARS™ Battlefront II (Classic, 2005)
Shared: Action · Shooter · Space

Transience
Shared: PvE · Shooter · Action

Alien Shooter 2: Reloaded
Shared: Shoot 'Em Up · PvE · Shooter

Battlefield™ 6
Shared: Action · Shooter · Singleplayer

Deep Rock Galactic
Shared: PvE · Shooter · Action

Crysis 2 Remastered
Shared: Action · Shooter · Shoot 'Em Up

Jump Space
Shared: PvE · Action · Space

Call of Duty®
Shared: Shooter · Action · Tactical

Snake Force
Shared: Action · Shooter · 3D

Crysis 3 Remastered
Shared: Action · Shooter · Sci-fi

Call of Duty®: Modern Warfare®
Shared: Action · Shooter · Tactical

STAR WARS™ Republic Commando™
Shared: Action · Shooter · Tactical

WARDOGS
Shared: Action · Shooter · Tactical

Gray Zone Warfare
Shared: Tactical · Shooter · PvE