Games like M.A.R.S.
Games like M.A.R.S. include ARC Raiders, PUBG: BATTLEGROUNDS, Marvel Rivals, HELLDIVERS™ 2, and Warframe. We matched them by the tags players give M.A.R.S. on Steam (Third-Person Shooter, PvE, Competitive, Shooter, and Character Customization): closest matches first, and among equally close ones the better-known games.

ARC Raiders
Shared: PvE · Third-Person Shooter · PvP

PUBG: BATTLEGROUNDS
Shared: Shooter · Third-Person Shooter · PvP

Marvel Rivals
Shared: Third-Person Shooter · PvP · Competitive

HELLDIVERS™ 2
Shared: PvE · Third-Person Shooter · Shooter

Warframe
Shared: Third-Person Shooter · PvE · Third Person

The Forever Winter
Shared: PvE · Third-Person Shooter · Horror

World of Warships
Shared: Third-Person Shooter · Shooter · PvP

Predecessor
Shared: Competitive · PvE · PvP

The Callisto Protocol™
Shared: Third-Person Shooter · Horror · Shooter

Rogue Company
Shared: Third-Person Shooter · Shooter · PvP

Mecha BREAK
Shared: PvP · Third-Person Shooter · Character Customization

NARAKA: BLADEPOINT
Shared: PvP · Character Customization · Female Protagonist

Military Conflict: Vietnam
Shared: Third-Person Shooter · PvP · PvE

Farlight 84
Shared: Third-Person Shooter · Shooter · PvP

Strinova
Shared: Third-Person Shooter · Shooter · PvP

Aliens: Fireteam Elite
Shared: Third-Person Shooter · Shooter · Character Customization

Resident Evil 3
Shared: Female Protagonist · Horror · Third-Person Shooter

Gears of War: E-Day
Shared: Third-Person Shooter · Female Protagonist · Shooter

Starward
Shared: Third-Person Shooter · Female Protagonist · Shooter

Pixel Gun 3D: PC Edition
Shared: PvP · Shooter · Character Customization

World War Z
Shared: Third-Person Shooter · PvE · Shooter

Warhammer 40,000: Space Marine 2
Shared: Third-Person Shooter · PvE · Third Person

The Killing Antidote
Shared: Third-Person Shooter · Female Protagonist · Shooter

THE FINALS
Shared: PvP · Shooter · Competitive