Games like GuildMestar
Games like GuildMestar include Monster Train, Slay the Spire 2, Slay the Spire, Balatro, and Griftlands. We matched them by the tags players give GuildMestar on Steam (Card Battler, Roguelite, Trading, Party-Based RPG, and Turn-Based Tactics): closest matches first, and among equally close ones the better-known games.

Monster Train
Shared: Card Battler · Roguelite · Turn-Based Tactics

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

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

Balatro
Shared: Card Game · Roguelite · Strategy

Griftlands
Shared: Card Battler · Roguelite · Card Game

Mewgenics
Shared: Roguelite · Turn-Based Tactics · Turn-Based Strategy

Inscryption
Shared: Card Battler · Card Game · Roguelite

Cross Blitz
Shared: Roguelite · Card Battler · Card Game

Journey to the West
Shared: Card Battler · Roguelite · Party-Based RPG

Dream of Corpse Lady
Shared: Card Battler · Strategy · Card Game

Wildfrost
Shared: Card Battler · Roguelite · Turn-Based Tactics

LONESTAR
Shared: Card Battler · Turn-Based Tactics · Strategy

Morimens
Shared: Card Battler · Roguelite · Party-Based RPG

Stacklands
Shared: Roguelite · Card Battler · Card Game

Wildermyth
Shared: Party-Based RPG · Turn-Based Tactics · Roguelite

StarVaders
Shared: Roguelite · Turn-Based Tactics · Card Game

As We Descend
Shared: Card Battler · Roguelite · Turn-Based Tactics

Roguebook
Shared: Roguelite · Card Game · Strategy

9 Kings
Shared: Strategy · Roguelite · Card Game

Into the Breach
Shared: Strategy · Turn-Based Tactics · Turn-Based Strategy

Black Book
Shared: Card Battler · Turn-Based Tactics · Roguelite

Darkest Dungeon® II
Shared: Roguelite · Turn-Based Tactics · Party-Based RPG

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

Ratropolis
Shared: Card Battler · Roguelite · Strategy