Forge is a computer game for Magic that allows you to play Magic against a computer opponent utilizing it's AI. Forge is open source and free to download. The project's blog announced today that they released a new version of Forge with 150 new cards, taking Forge's supported card count to 3,572. The software is in Java so it can be run on most platforms, PC, Mac, Linux etc.

You can read the full blog post, which also covers bug fixes in the current version. Or visit the Google project to download the game.