Games like Three Kingdoms 21
Games like Three Kingdoms 21 include The Zachtronics Solitaire Collection, Balatro, Stacklands, Plants vs. Zombies GOTY Edition, and Rana Card. We matched them by the tags players give Three Kingdoms 21 on Steam (Casual, Card Game, Solitaire, 2D, and PvE): closest matches first, and among equally close ones the better-known games.

The Zachtronics Solitaire Collection
Shared: Casual · Solitaire · Card Game

Balatro
Shared: Card Game · Singleplayer · Casual

Stacklands
Shared: Card Game · Solitaire · 2D

Plants vs. Zombies GOTY Edition
Shared: Casual · Singleplayer · 2D

Rana Card
Shared: Casual · Card Game · 2D

UNO
Shared: Card Game · Casual · Singleplayer

Ballionaire
Shared: Casual · 2D · Singleplayer

Poker Night at the Inventory
Shared: Casual · Card Game · Singleplayer

Peggle Deluxe
Shared: Casual · 2D · Singleplayer

One Turn Kill
Shared: Card Game · 2D · Solitaire

Zup! S
Shared: Casual · 2D · Singleplayer

Vampire Survivors
Shared: 2D · Casual · Singleplayer

Faerie Solitaire
Shared: Casual · Solitaire · Card Game

Bloons TD 6
Shared: Casual · Singleplayer · 2D

Ratropolis
Shared: 2D · Card Game · Singleplayer

Kingdom Rush - Tower Defense
Shared: 2D · Casual · Singleplayer

Dead Man's Draw
Shared: Casual · Card Game · PvE

DJMAX RESPECT V
Shared: Casual · 2D · Singleplayer

Game Dev Tycoon
Shared: Casual · Singleplayer · 2D

Melvor Idle
Shared: Casual · Singleplayer · 2D

Slay the Spire
Shared: Card Game · Singleplayer · 2D

DAVE THE DIVER
Shared: Casual · Singleplayer · 2D