Riftbound card game can simulate any computer with legal decks
Riftbound is Turing Complete
Computational Complexity
Summary
Some games are more complex than they seem, and this card game called Riftbound is one of them. The authors show you can set up the pieces and use legal decks to simulate a completely universal computer inside the game. This means, within the rules and one turn, the game can perform any calculation a computer can, given the right setup. It highlights unexpected depth in the game’s design and complexity.
What this means in practice
- •For game designers: Recognize that trading card games like Riftbound can represent arbitrary computations influencing design of complex mechanics.
- •For computational theorists: Use this example to illustrate how game rules can encode universal computation in teaching or analysis.
A theory result. No direct application yet.
Authors
Nathan Dalaklis, Beckett Fields
Abstract
Riftbound: League of Legends Trading Card Game is a trading card game about capturing and holding locations in a king-of-the-hill style contest. Originally released in China in August of 2025, and later released in the United States in October of 2025, the game has been well received for its depth and complexity. In this paper we demonstrate a facet of this complexity by providing sequences of valid game states which construct Universal Turing machines within the game. Each of these machines are constructed with tournament legal decks at the time of writing and strategies assigned are directed by the game state. We also show that given an appropriate board state the machine may be constructed and the computation may be performed in one game turn.