Games like .Forty-Five
Games like .Forty-Five include Slay the Spire, Balatro, Slay the Spire 2, Monster Train, and Wildfrost. We matched them by the tags players give .Forty-Five on Steam (Roguelike Deckbuilder, Free to Play, Western, Card Game, and Roguelite): closest matches first, and among equally close ones the better-known games.

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

Balatro
Shared: Roguelike Deckbuilder · Card Game · Roguelike

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

Monster Train
Shared: Card Game · Roguelite · Deckbuilding

Wildfrost
Shared: Roguelike Deckbuilder · Card Game · Roguelite

9 Kings
Shared: Roguelike Deckbuilder · Card Game · Roguelike

Dicey Dungeons
Shared: Roguelike Deckbuilder · Roguelite · Deckbuilding

Monster Train 2
Shared: Roguelike Deckbuilder · Card Game · Roguelike

StarVaders
Shared: Roguelike Deckbuilder · Roguelite · Deckbuilding

Die in the Dungeon
Shared: Roguelike Deckbuilder · Roguelike · Card Game

Across the Obelisk
Shared: Roguelike Deckbuilder · Card Game · Roguelike

As We Descend
Shared: Roguelike Deckbuilder · Card Game · Roguelike

Black Jacket
Shared: Roguelike Deckbuilder · Card Game · Roguelike

LONESTAR
Shared: Roguelike Deckbuilder · Roguelike · Turn-Based Tactics

Hand of Fate
Shared: Roguelike Deckbuilder · Card Game · Roguelike

Magic: The Gathering Arena
Shared: Free to Play · Card Game · Deckbuilding

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

Alina of the Arena
Shared: Roguelike Deckbuilder · Roguelike · Card Game

Dungeons & Degenerate Gamblers
Shared: Roguelike Deckbuilder · Card Game · Roguelike

RACCOIN: Coin Pusher Roguelike
Shared: Roguelike Deckbuilder · Roguelike · Deckbuilding

Roguebook
Shared: Card Game · Deckbuilding · Roguelite

Touhou: Lost Branch of Legend
Shared: Roguelike Deckbuilder · Card Game · Roguelike

Astrea: Six-Sided Oracles
Shared: Roguelike Deckbuilder · Card Game · Roguelike

Fights in Tight Spaces
Shared: Roguelike Deckbuilder · Deckbuilding · Card Game