Yes Zerg, that was the change. It made it a lot easier to move around, and fixed some bugs with moving platforms. And when you pause the scenario, it removes the overlay so you can work on the other actors, and then puts it back when you resume. I probably should change that, but it is useful when testing!

Very nice, its cool to see a Powder Game fan on Greenfoot. Are you going for an air engine like in the powder game? If so, you definitely have some work to do, but this is a Great start!

Wow, this is a really weird error, i can't find anything wrong with your code or your files. Um... Try putting all your sounds in a folder labeled 'sounds', that's the only difference i can find with yours from all the others.