mage

Why we included this project

XMage is the most complete open-source way to play Magic: The Gathering against a computer. It enforces the game's actual rules across tens of thousands of cards, so a Commander game, a draft tournament, or a quick duel runs itself without you tracking phases and priority by hand. The bundled computer opponents give you a solo practice mode, and the client-server design lets you host your own server for games with friends or join public ones. It's also a substantial Java codebase worth reading if you want to see how a complex card game encodes its rules engine and AI decision-making. Just know it's a game engine, not a general-purpose AI library, so it won't help you build other kinds of AI. For MTG automation, it's the most complete option available.