Games like Neptunia Shooter
Games like Neptunia Shooter include Mirage Feathers, Rabi-Ribi, Planes, Bullets and Vodka, Vampire Survivors, and DRAINUS. We matched them by the tags players give Neptunia Shooter on Steam (Bullet Hell, Action, Shoot 'Em Up, Anime, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

Mirage Feathers
Shared: Bullet Hell · Anime · Cute

Rabi-Ribi
Shared: Bullet Hell · Anime · Pixel Graphics

Planes, Bullets and Vodka
Shared: Action · Shoot 'Em Up · Bullet Hell

Vampire Survivors
Shared: Bullet Hell · Pixel Graphics · 2D

DRAINUS
Shared: Action · Shoot 'Em Up · Bullet Hell

Touhou Koumakyou: New Classic - the Embodiment of Scarlet Devil
Shared: Bullet Hell · Shoot 'Em Up · Action

LUFTRAUSERS
Shared: Bullet Hell · Action · Pixel Graphics

Bit Blaster XL
Shared: Bullet Hell · Shoot 'Em Up · Action

ZeroRanger
Shared: Bullet Hell · Shoot 'Em Up · Action

Dimension Tripper Neptune: TOP NEP
Shared: Action · Bullet Hell · Shoot 'Em Up

BALL x PIT
Shared: Action · Bullet Hell · Shoot 'Em Up

Muse Dash
Shared: Anime · Cute · Female Protagonist

Touhou Hero of Ice Fairy
Shared: Bullet Hell · Anime · Female Protagonist

Last Command
Shared: Bullet Hell · Anime · Cute

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

Mushihimesama
Shared: Bullet Hell · Shoot 'Em Up · Action

BLUE REVOLVER
Shared: Bullet Hell · Shoot 'Em Up · Action

DoDonPachi Resurrection
Shared: Bullet Hell · Shoot 'Em Up · Action

Touhou Kouryudou ~ Unconnected Marketeers.
Shared: Bullet Hell · Action · Shoot 'Em Up

Phantom Breaker: Battle Grounds Classic
Shared: Action · Anime · Pixel Graphics

Huntdown
Shared: Action · Pixel Graphics · Shoot 'Em Up

TEVI
Shared: Bullet Hell · Anime · Pixel Graphics

Deathsmiles
Shared: Bullet Hell · Action · Shoot 'Em Up

DJMAX RESPECT V
Shared: Action · Anime · Cute