Games like Nine Heavens
Games like Nine Heavens include Vampire Survivors, Hades, Megabonk, 20 Minutes Till Dawn, and Magicraft. We matched them by the tags players give Nine Heavens on Steam (Roguelite, Casual, Bullet Hell, Magic, and Mythology): closest matches first, and among equally close ones the better-known games.

Vampire Survivors
Shared: Roguelite · Bullet Hell · Action Roguelike

Hades
Shared: Roguelite · Action Roguelike · Mythology

Megabonk
Shared: Roguelite · Bullet Hell · Action Roguelike

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

Magicraft
Shared: Roguelite · Bullet Hell · Action Roguelike

Black Myth: Wukong
Shared: Mythology · Action · RPG

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

Hades II
Shared: Roguelite · Action · Mythology

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

The Spell Brigade
Shared: Roguelite · Bullet Hell · Action Roguelike

Goobies
Shared: Roguelite · Bullet Hell · Casual

Noobs Want to Live
Shared: Bullet Hell · Casual · Roguelite

Soulstone Survivors
Shared: Roguelite · Bullet Hell · Action Roguelike

Apocalypse Party
Shared: Casual · Roguelite · Bullet Hell

Cultivation Story: Reincarnation
Shared: Roguelite · Bullet Hell · Action Roguelike

UnderMine
Shared: Roguelite · Action Roguelike · Action

BALL x PIT
Shared: Roguelite · Bullet Hell · Action

Brotato
Shared: Bullet Hell · Action Roguelike · Roguelite

Nordic Ashes: Survivors of Ragnarok
Shared: Roguelite · Bullet Hell · Action Roguelike

God of War
Shared: Action · Mythology · Singleplayer

Shape of Dreams
Shared: Roguelite · Action Roguelike · Action

God Of Weapons
Shared: Roguelite · Bullet Hell · Action Roguelike

Deep Rock Galactic: Survivor
Shared: Roguelite · Bullet Hell · Action Roguelike

Spirit Hunters: Infinite Horde
Shared: Roguelite · Bullet Hell · Action Roguelike