Games like Star99
Games like Star99 include Huntdown, Broforce, METAL SLUG, Streets of Rage 4, and Blazing Chrome. We matched them by the tags players give Star99 on Steam (Side Scroller, Shoot 'Em Up, Battle Royale, Arcade, and 2D): closest matches first, and among equally close ones the better-known games.
Huntdown
Shared: Side Scroller · Shoot 'Em Up · Action
Broforce
Shared: Action · 2D · Side Scroller
METAL SLUG
Shared: Side Scroller · Arcade · Shoot 'Em Up
Streets of Rage 4
Shared: Action · 2D · Side Scroller
Blazing Chrome
Shared: Side Scroller · Shoot 'Em Up · Action
METAL SLUG X
Shared: Arcade · Shoot 'Em Up · Action
METAL SLUG 3
Shared: Side Scroller · Arcade · Action
Guns, Gore & Cannoli
Shared: Side Scroller · Action · 2D
BALL x PIT
Shared: Arcade · Action · Shoot 'Em Up
Shovel Knight: Treasure Trove
Shared: 2D · Pixel Graphics · Side Scroller
Apex Legends™
Shared: Battle Royale · PvP · Action
UFO 50
Shared: Arcade · 2D · Action
METAL SLUG 2
Shared: Side Scroller · Shoot 'Em Up · Arcade
SANABI
Shared: Action · Pixel Graphics · Cyberpunk
Cyberhunt
Shared: Shoot 'Em Up · Action · Arcade
PUBG: BATTLEGROUNDS
Shared: Battle Royale · PvP · Action
Alex Jones: NWO Wars
Shared: Shoot 'Em Up · Arcade · Side Scroller
Jets'n'Guns Gold
Shared: Shoot 'Em Up · Side Scroller · Action
Planes, Bullets and Vodka
Shared: Shoot 'Em Up · Action · Arcade
Teenage Mutant Ninja Turtles: Shredder's Revenge
Shared: Side Scroller · 2D · Arcade
NARAKA: BLADEPOINT
Shared: Battle Royale · PvP · Action
Kung Fury: Street Rage - Ultimate Edition
Shared: Arcade · Side Scroller · Action
Sonic Mania
Shared: 2D · Side Scroller · Pixel Graphics
ZeroRanger
Shared: Shoot 'Em Up · Arcade · Action