Games like Pumpkin head
Games like Pumpkin head include SANABI, Broforce, Skul: The Hero Slayer, Huntdown, and Door Kickers: Action Squad. We matched them by the tags players give Pumpkin head on Steam (Side Scroller, Action, 2D Platformer, Shooter, and Action-Adventure): closest matches first, and among equally close ones the better-known games.

SANABI
Shared: Action · 2D Platformer · Pixel Graphics

Broforce
Shared: Action · Pixel Graphics · 2D

Skul: The Hero Slayer
Shared: Action · Pixel Graphics · 2D

Huntdown
Shared: Side Scroller · Action · Shooter

Door Kickers: Action Squad
Shared: 2D Platformer · Action · Pixel Graphics

Momodora: Moonlit Farewell
Shared: Side Scroller · Pixel Graphics · Action-Adventure

Terminator 2D: NO FATE
Shared: Side Scroller · 2D Platformer · Action

Katana ZERO
Shared: Action · Pixel Graphics · 2D Platformer

Alex Jones: NWO Wars
Shared: Action · 2D Platformer · Shooter

Blasphemous 2
Shared: Side Scroller · 2D Platformer · Fantasy

Mina the Hollower
Shared: Action-Adventure · 2D Platformer · Pixel Graphics

Momodora: Reverie Under The Moonlight
Shared: Side Scroller · 2D Platformer · Pixel Graphics

Teenage Mutant Ninja Turtles: Shredder's Revenge
Shared: Side Scroller · Pixel Graphics · 2D

BlazBlue Entropy Effect
Shared: Action · 2D · Action-Adventure

Blade Assault
Shared: Action · 2D Platformer · Pixel Graphics

BioShock Infinite
Shared: Action · Shooter · Singleplayer

Gunvolt Chronicles: Luminous Avenger iX 2
Shared: Action · 2D Platformer · Action-Adventure

NINJA GAIDEN: Ragebound
Shared: Action · 2D Platformer · Side Scroller

Moonscars
Shared: Action · 2D Platformer · Action-Adventure

Gravity Circuit
Shared: Action · 2D Platformer · 2D

Anomaly Agent
Shared: Side Scroller · 2D Platformer · Action-Adventure

Bloodstained: Curse of the Moon
Shared: Action · Side Scroller · Pixel Graphics

Prince of Persia The Lost Crown
Shared: 2D Platformer · Action · Side Scroller

My Friend Pedro
Shared: Action · Shooter · Side Scroller