Games like Mystic 6
Games like Mystic 6 include Slay the Spire, Balatro, Slay the Spire 2, 9 Kings, and Inscryption. We matched them by the tags players give Mystic 6 on Steam (Roguelite, Card Game, Deckbuilding, Card Battler, and Strategy): closest matches first, and among equally close ones the better-known games.

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

Balatro
Shared: Card Game · Deckbuilding · Roguelite

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

9 Kings
Shared: Strategy · Card Game · Deckbuilding

Inscryption
Shared: Card Game · Card Battler · Deckbuilding

Dicey Dungeons
Shared: Roguelite · Deckbuilding · Card Battler

Monster Train
Shared: Roguelite · Card Game · Card Battler

Griftlands
Shared: Roguelite · Card Battler · Deckbuilding

Ratropolis
Shared: Deckbuilding · Roguelite · Card Battler

DICEOMANCER
Shared: Card Game · Strategy · Card Battler

Super Fantasy Kingdom
Shared: Roguelite · Strategy · Card Game

Stacklands
Shared: Card Game · Roguelite · Card Battler

Dungeons & Degenerate Gamblers
Shared: Card Game · Deckbuilding · Strategy

Roguebook
Shared: Card Game · Deckbuilding · Roguelite

Die in the Dungeon
Shared: Deckbuilding · Card Game · Strategy

Cross Blitz
Shared: Roguelite · Deckbuilding · Card Game

Wildfrost
Shared: Card Game · Card Battler · Roguelite

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

Loop Hero
Shared: Roguelite · Deckbuilding · Card Game

He is Coming
Shared: Roguelite · Strategy · Card Game

Breachway
Shared: Card Game · Strategy · Deckbuilding

RACCOIN: Coin Pusher Roguelike
Shared: Deckbuilding · Strategy · Roguelite

Journey to the West
Shared: Roguelite · Card Battler · Card Game

My Card Is Better Than Your Card!
Shared: Card Game · Deckbuilding · Roguelite