Games like ShootOut(SystemD)
Games like ShootOut(SystemD) include STAR WARS™ Battlefront™ II, HELLDIVERS™ 2, Warframe, STAR WARS™ Battlefront II (Classic, 2005), and Dead Space. We matched them by the tags players give ShootOut(SystemD) on Steam (Singleplayer, Sci-fi, Shooter, Third-Person Shooter, and Action): closest matches first, and among equally close ones the better-known games.

STAR WARS™ Battlefront™ II
Shared: Singleplayer · Shooter · Sci-fi

HELLDIVERS™ 2
Shared: Third-Person Shooter · Shooter · Sci-fi

Warframe
Shared: Third-Person Shooter · Action · Action RPG

STAR WARS™ Battlefront II (Classic, 2005)
Shared: Shooter · Action · Sci-fi

Dead Space
Shared: Third-Person Shooter · Sci-fi · Singleplayer

Dead Space (2008)
Shared: Sci-fi · Action · Singleplayer

Warhammer 40,000: Space Marine - Anniversary Edition
Shared: Sci-fi · Third-Person Shooter · Action

Mass Effect™ Legendary Edition
Shared: Sci-fi · Singleplayer · Space

Mass Effect (2007)
Shared: Sci-fi · Singleplayer · Action

Warhammer 40,000: Space Marine 2
Shared: Action · Third-Person Shooter · Sci-fi

Vanquish
Shared: Sci-fi · Singleplayer · Third-Person Shooter

PRAGMATA
Shared: Sci-fi · Third-Person Shooter · Action

Dead Space™ 2
Shared: Shooter · Third-Person Shooter · Action

Grand Theft Auto V Legacy
Shared: Action · Shooter · Singleplayer

Star Wars Outlaws
Shared: Singleplayer · Action · Sci-fi

The Callisto Protocol™
Shared: Sci-fi · Third-Person Shooter · Shooter

Risk of Rain 2
Shared: Third-Person Shooter · Action · Action Roguelike

Mass Effect™ 3 N7 Digital Deluxe Edition (2012)
Shared: Sci-fi · Singleplayer · Action

Dead Space™ 3
Shared: Sci-fi · Action · Shooter

Quantum Break
Shared: Sci-fi · Singleplayer · Action

Marvel's Guardians of the Galaxy
Shared: Singleplayer · Action · Third-Person Shooter

STAR WARS Jedi: Survivor™
Shared: Singleplayer · Action · Sci-fi

Half-Life 2
Shared: Sci-fi · Singleplayer · Action

Just Cause™ 3
Shared: Action · Singleplayer · Third-Person Shooter