Games like GUN RAT classic
Games like GUN RAT classic include SANABI, Rogue Legacy 2, Broforce, Sonic Origins, and Ori and the Will of the Wisps. We matched them by the tags players give GUN RAT classic on Steam (Casual, Adventure, Action, Arcade, and Platformer): closest matches first, and among equally close ones the better-known games.

SANABI
Shared: Action · Adventure · 2D Platformer

Rogue Legacy 2
Shared: Arcade · Action · Platformer

Broforce
Shared: Action · Platformer · 2D

Sonic Origins
Shared: Action · Adventure · Casual

Ori and the Will of the Wisps
Shared: Platformer · Action · Adventure

Skul: The Hero Slayer
Shared: Action · Platformer · Indie

Sonic Superstars
Shared: Action · Adventure · Casual

The Messenger
Shared: Platformer · Action · Metroidvania

Shovel Knight: Treasure Trove
Shared: Platformer · Adventure · Action

Hollow Knight
Shared: Platformer · Metroidvania · Adventure

Sonic Mania
Shared: Platformer · Adventure · Action

F.I.S.T.: Forged In Shadow Torch
Shared: Action · Adventure · Platformer

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

Bloodstained: Curse of the Moon
Shared: Action · Platformer · Adventure

Downwell
Shared: Platformer · Arcade · Action

UFO 50
Shared: Action · Arcade · Adventure

Dust: An Elysian Tail
Shared: Action · Platformer · Adventure

Dead Cells
Shared: Adventure · Metroidvania · Platformer

Exit the Gungeon
Shared: Arcade · Action · Adventure

Gato Roboto
Shared: Action · Adventure · Metroidvania

Super Mombo Quest
Shared: Adventure · Action · Arcade

Axiom Verge
Shared: Platformer · Action · Adventure

Owlboy
Shared: Adventure · Platformer · Action

Axiom Verge 2
Shared: Adventure · Action · Platformer