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

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

Slay the Spire 2
Shared: Deckbuilding · Roguelike Deckbuilder · Strategy

Balatro
Shared: Roguelike Deckbuilder · Deckbuilding · Strategy

Dicey Dungeons
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

9 Kings
Shared: Strategy · Deckbuilding · Roguelike Deckbuilder

Monster Train
Shared: Card Battler · Deckbuilding · Roguelite

Die in the Dungeon
Shared: Deckbuilding · Roguelike Deckbuilder · Strategy

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

Wildfrost
Shared: Roguelike Deckbuilder · Card Battler · Deckbuilding

Dungeons & Degenerate Gamblers
Shared: Roguelike Deckbuilder · Deckbuilding · Strategy

Inscryption
Shared: Card Battler · Deckbuilding · Roguelite

Griftlands
Shared: Card Battler · Deckbuilding · Roguelite

DICEOMANCER
Shared: Roguelike Deckbuilder · Card Battler · Strategy

Super Fantasy Kingdom
Shared: Strategy · Roguelite · Deckbuilding

Ratropolis
Shared: Deckbuilding · Card Battler · Roguelite

Luck be a Landlord
Shared: Roguelike Deckbuilder · Deckbuilding · Roguelite

Breachway
Shared: Deckbuilding · Roguelike Deckbuilder · Strategy

Roguebook
Shared: Deckbuilding · Strategy · Singleplayer

Vault of the Void
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

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

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

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

Cubic Cosmos
Shared: Roguelike Deckbuilder · Deckbuilding · Card Battler

Touhou: Lost Branch of Legend
Shared: Roguelike Deckbuilder · Card Battler · Strategy