Games like Souterrain
Games like Souterrain include Balatro, Slay the Spire, Slay the Spire 2, 9 Kings, and Dungeons & Degenerate Gamblers. We matched them by the tags players give Souterrain on Steam (Card Game, Strategy, Roguelike, Indie, and Casual): closest matches first, and among equally close ones the better-known games.

Balatro
Shared: Card Game · Roguelike · Strategy

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

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

9 Kings
Shared: Strategy · Card Game · Roguelike

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

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

Dicey Dungeons
Shared: Roguelike Deckbuilder · Roguelike · Indie

Wildfrost
Shared: Card Game · Roguelike Deckbuilder · Roguelike

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

Across the Obelisk
Shared: Casual · Card Game · Roguelike

DICEOMANCER
Shared: Card Game · Strategy · Roguelike Deckbuilder

The Binding of Isaac: Rebirth
Shared: Roguelike · Indie · Replay Value

Black Jacket
Shared: Card Game · Roguelike · Roguelike Deckbuilder

Ratropolis
Shared: Strategy · Card Game · Deckbuilding

Inscryption
Shared: Card Game · Deckbuilding · Roguelike

Breachway
Shared: Strategy · Card Game · Roguelike

FTL: Faster Than Light
Shared: Roguelike · Strategy · Indie

Monster Train
Shared: Card Game · Roguelike · Deckbuilding

Roguebook
Shared: Card Game · Indie · Strategy

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

Super Fantasy Kingdom
Shared: Strategy · Roguelike · Card Game

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

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

My Card Is Better Than Your Card!
Shared: Card Game · Roguelike · Strategy