With much time and effort. Blarrgh those treasure hunting levels ;_; But Green Hill was unlocked, yes, and a neat remake of the stage as well. =) Chao is also good fun, heh - I have a friend who spent hundred and hundreds of hours on them. XD (And had a whole bunch of chaos chao and iirc a Tails chao and other oddities...)
I shall look into that tune when I get home then I suppose. City Escape and Live and Learn make for formidable musical opponents though... ;p