Games like Spitfire - Moonpie´s Mission
Games like Spitfire - Moonpie´s Mission include Vampire Survivors, Megabonk, BALL x PIT, Halls of Torment, and Broforce. We matched them by the tags players give Spitfire - Moonpie´s Mission on Steam (On-Rails Shooter, Action, Side Scroller, Arcade, and Bullet Hell): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Bullet Hell · Roguelite · Pixel Graphics

Megabonk
Shared: Roguelite · Bullet Hell · Action

BALL x PIT
Shared: Action · Arcade · Roguelite

Halls of Torment
Shared: Bullet Hell · Roguelite · Action

Broforce
Shared: Action · Pixel Graphics · Side Scroller

Warhammer 40,000: Boltgun
Shared: Action · Pixel Graphics · Arcade

Mirage Feathers
Shared: On-Rails Shooter · Bullet Hell · Action

Skul: The Hero Slayer
Shared: Action · Pixel Graphics · Roguelite

LUFTRAUSERS
Shared: Action · Arcade · Bullet Hell

Exit the Gungeon
Shared: Action · Arcade · Bullet Hell

Planes, Bullets and Vodka
Shared: Action · Bullet Hell · Arcade

Huntdown
Shared: Side Scroller · Action · Pixel Graphics

METAL SLUG 3
Shared: Action · Arcade · Side Scroller

Boneraiser Minions
Shared: Bullet Hell · Roguelite · Pixel Graphics

Alex Jones: NWO Wars
Shared: Action · Arcade · Side Scroller

Rogue Legacy 2
Shared: Arcade · Action · Roguelite

Dimension Tripper Neptune: TOP NEP
Shared: Action · On-Rails Shooter · Arcade

METAL SLUG
Shared: Action · Arcade · Side Scroller

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

Death Must Die
Shared: Bullet Hell · Roguelite · Action

Kung Fury: Street Rage - Ultimate Edition
Shared: Arcade · Action · Side Scroller

Shovel Knight: Treasure Trove
Shared: Pixel Graphics · Action · Side Scroller

Nova Drift
Shared: Bullet Hell · Arcade · Roguelite

Noobs Want to Live
Shared: Action · Bullet Hell · Pixel Graphics