First of all, the intended audience was born about two and a half weeks ago - so there is still a little time to get things working.
So far, there are XML parsers for level files and object classes, and the physics engine is usable for quite a few levels.
Unfortunately, there is no user interaction up to now, as the levels are simply loaded from the XML file and subjected to the physics engine. There are also no complex objects so far, just movable and non-movable blocks, balls and polygons.
Background music is also possible, but commented out for now.