Games like Spell Spiral
Games like Spell Spiral include Rabbit and Steel, Slay the Spire, Slay the Spire 2, Yu-Gi-Oh! Legacy of the Duelist, and Inscryption. We matched them by the tags players give Spell Spiral on Steam (Action, Shooter, Bullet Hell, Deckbuilding, and Card Game): closest matches first, and among equally close ones the better-known games.

Rabbit and Steel
Shared: Bullet Hell · Cute · Action

Slay the Spire
Shared: Card Game · Deckbuilding · Card Battler

Slay the Spire 2
Shared: Deckbuilding · Card Game · Card Battler

Yu-Gi-Oh! Legacy of the Duelist
Shared: Card Game · Deckbuilding · Card Battler

Inscryption
Shared: Card Game · Card Battler · Deckbuilding

Vampire Crawlers: The Turbo Wildcard from Vampire Survivors
Shared: Deckbuilding · Card Battler · Action

One Step From Eden
Shared: Deckbuilding · Action · Card Battler

ROUNDS
Shared: Action · Deckbuilding · Card Battler

Touhou Juuouen 〜 Unfinished Dream of All Living Ghost.
Shared: Action · Bullet Hell · Shooter

BioShock Infinite
Shared: Action · Shooter · Fantasy

永远消失的幻想乡 ~ The Disappearing of Gensokyo
Shared: Bullet Hell · Action · Cute

Balatro
Shared: Card Game · Deckbuilding · Card Battler

Touhou: Scarlet Curiosity
Shared: Action · Bullet Hell · Fantasy

Magic: The Gathering Arena
Shared: Card Game · Deckbuilding · Fantasy

Touhou Koumakyou: New Classic - the Embodiment of Scarlet Devil
Shared: Bullet Hell · Action · Shooter

Touhou Kouryudou ~ Unconnected Marketeers.
Shared: Action · Bullet Hell · Shooter

My Friend Pedro
Shared: Action · Shooter · Indie

Bit Blaster XL
Shared: Bullet Hell · Shooter · Action

Exit the Gungeon
Shared: Action · Bullet Hell · Shooter

Rabi-Ribi
Shared: Bullet Hell · Action · Cute

Paladins®
Shared: Shooter · Action · Fantasy

The Bazaar
Shared: Deckbuilding · Card Game · Card Battler

Ratropolis
Shared: Deckbuilding · Card Battler · Card Game

Hand of Fate 2
Shared: Action · Deckbuilding · Card Game