Games like Decisive Decks
Games like Decisive Decks include Slay the Spire 2, Slay the Spire, Balatro, Monster Train, and 9 Kings. We matched them by the tags players give Decisive Decks on Steam (Roguelike Deckbuilder, Deckbuilding, Turn-Based Combat, World War II, and Naval Combat): closest matches first, and among equally close ones the better-known games.

Slay the Spire 2
Shared: Deckbuilding · Roguelike Deckbuilder · Card Game

Slay the Spire
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Balatro
Shared: Roguelike Deckbuilder · Deckbuilding · Card Game

Monster Train
Shared: Deckbuilding · Card Battler · Roguelite

9 Kings
Shared: Deckbuilding · Roguelike Deckbuilder · Card Game

Dicey Dungeons
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Wildfrost
Shared: Roguelike Deckbuilder · Card Battler · Deckbuilding

Die in the Dungeon
Shared: Deckbuilding · Roguelike Deckbuilder · Turn-Based Combat

Astrea: Six-Sided Oracles
Shared: Roguelike Deckbuilder · Card Battler · Deckbuilding

Decktamer
Shared: Roguelike Deckbuilder · Turn-Based Combat · Deckbuilding

As We Descend
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Inscryption
Shared: Deckbuilding · Card Battler · Card Game

Griftlands
Shared: Deckbuilding · Card Battler · Roguelite

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

StarVaders
Shared: Roguelike Deckbuilder · Deckbuilding · Roguelite

Library Of Ruina
Shared: Deckbuilding · Turn-Based Combat · Card Game

DICEOMANCER
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Hadean Tactics
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Breachway
Shared: Deckbuilding · Roguelike Deckbuilder · Turn-Based Combat

Dungeons & Degenerate Gamblers
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Monster Slayers
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Super Fantasy Kingdom
Shared: Deckbuilding · Roguelike Deckbuilder · Roguelite

Dice & Fold
Shared: Roguelike Deckbuilder · Turn-Based Combat · Card Battler

LONESTAR
Shared: Roguelike Deckbuilder · Card Battler · Turn-Based Combat