Games like Zunius
Games like Zunius include Vampire Survivors, Nova Drift, Star of Providence, Hades, and BALL x PIT. We matched them by the tags players give Zunius on Steam (Bullet Hell, Indie, Action Roguelike, Roguelite, and Shoot 'Em Up): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Bullet Hell · Action Roguelike · Roguelite

Nova Drift
Shared: Bullet Hell · Shoot 'Em Up · Roguelite

Star of Providence
Shared: Bullet Hell · Roguelite · Action Roguelike

Hades
Shared: Action Roguelike · Indie · Roguelite

BALL x PIT
Shared: Bullet Hell · Roguelite · Action Roguelike

Nuclear Throne
Shared: Action Roguelike · Indie · Bullet Hell

Skul: The Hero Slayer
Shared: Indie · Action Roguelike · Roguelite

Megabonk
Shared: Action Roguelike · Indie · Bullet Hell

Enter the Gungeon
Shared: Bullet Hell · Action Roguelike · Indie

The Binding of Isaac: Rebirth
Shared: Action Roguelike · Indie · 2D

20 Minutes Till Dawn
Shared: Bullet Hell · Action Roguelike · Roguelite

Halls of Torment
Shared: Bullet Hell · Action Roguelike · Roguelite

Jets'n'Guns Gold
Shared: Shoot 'Em Up · Indie · Bullet Hell

The Void Rains Upon Her Heart
Shared: Bullet Hell · Indie · Action Roguelike

Roboquest
Shared: Action Roguelike · Roguelite · Shooter

Brotato
Shared: Bullet Hell · Action Roguelike · Roguelite

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

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

Realm of the Mad God Exalt
Shared: Bullet Hell · Action Roguelike · Indie

Death Must Die
Shared: Bullet Hell · Action Roguelike · Roguelite

Dungreed
Shared: Action Roguelike · Roguelite · Indie

LUFTRAUSERS
Shared: Bullet Hell · Indie · Shoot 'Em Up

I Am Legion: Stand Survivors
Shared: Bullet Hell · Action Roguelike · Roguelite

Risk of Rain 2
Shared: Action Roguelike · Roguelite · Action