Games like Platypus
Games like Platypus include Cuphead, METAL SLUG 3, ZeroRanger, METAL SLUG X, and Broforce. We matched them by the tags players give Platypus on Steam (Action, Shoot 'Em Up, Retro, Arcade, and Local Co-Op): closest matches first, and among equally close ones the better-known games.

Cuphead
Shared: Co-op · Local Co-Op · Great Soundtrack

METAL SLUG 3
Shared: Action · Arcade · Retro

ZeroRanger
Shared: Shoot 'Em Up · Action · Arcade

METAL SLUG X
Shared: Action · Arcade · Shoot 'Em Up

Broforce
Shared: Action · Co-op · Local Co-Op

METAL SLUG
Shared: Action · Arcade · Shoot 'Em Up

Streets of Rage 4
Shared: Action · Arcade · Indie

Revolution Ace
Shared: Action · Shoot 'Em Up · Local Co-Op

Ikaruga
Shared: Shoot 'Em Up · Action · Arcade

LUFTRAUSERS
Shared: Action · Arcade · Shoot 'Em Up

Blazing Chrome
Shared: Action · Retro · Shoot 'Em Up

Huntdown
Shared: Action · Shoot 'Em Up · Local Co-Op

Geometry Wars™ 3: Dimensions Evolved
Shared: Action · Shoot 'Em Up · Arcade

Sky Force Reloaded
Shared: Shoot 'Em Up · Arcade · Action

Star Saviors
Shared: Shoot 'Em Up · Action · Bullet Hell

METAL SLUG 2
Shared: Action · Arcade · Shoot 'Em Up

DARIUSBURST Chronicle Saviours
Shared: Shoot 'Em Up · Action · Arcade

Double Dragon: Neon
Shared: Action · Co-op · Arcade

Jets'n'Guns Gold
Shared: Shoot 'Em Up · Action · Great Soundtrack

Jamestown
Shared: Shoot 'Em Up · Local Co-Op · Action

Nex Machina
Shared: Action · Arcade · Shoot 'Em Up

Shovel Knight: Treasure Trove
Shared: Retro · Action · Great Soundtrack

The Bug Butcher
Shared: Action · Shoot 'Em Up · Arcade

PARTICLE MACE
Shared: Action · Arcade · Indie