Music shows Play button, which I click, it turns into Pause and then nothing happens.
Pong shows yellow/orange rectangle with what seems like a button, with its top edge striking through a (misplaced?) "Go" text. Nothing is clickable, left/right arrows have no effect.
(edit) I see it needs FF18, which I gather is a dev release. Perhaps you want to add compatible browser detection code? And complain accordingly.