Ciro Santilli Open source MtG engine implementation written in Java.
Seems to have an option to download art from internet as well.
Ciro Santilli wonders how legal it is. They very explicitly do not mention the words Magic: The Gathering anywhere.
Their UI does a good job at being self explanatory. Space is the shortcut to skip phases.
No online play.
TODO it appears to parse card functionality out of the human readable text! That's genius, as it helps automatically get new cards working, and squirt around legal issues.