This is a Forplay port of Microsoft's XNA Platformer Starter Kit example.
The original code and assets are licensed under the "Microsoft Permissive License" (see the .rtf file in this directory).
The code's a real mess, as I ported it from C# to Java in a matter of a few hours, but it makes a nice proof-of-concept.
Demo link: http://xna-platformer.appspot.com/Platformer.html