A few days ago, EA posted a demo for the next game made by the Far Cry developers, CryTek. The game, otherwise known as Crysis, is a 1.8 GB download and contains the Sandbox editor, which allows you to just play around with tools to make new levels and such. Then to test it out you can spawn yourself in them. A fun feature to be included in a demo.
The demo also contains the first Single Player level, known as Contact.
The Crysis Demo can be downloaded here. The full game comes out on November 16th.