Azure
Trust the recursion...
When you consider Stepmania vs. Guitar Hero DS (or whatever it's called) on the Pandora, the two are actually quite similar in terms of gameplay. Often times when people play Stepmania with a keyboard, they use 4 keys in the same row. A guitar hero clone would be pretty much the exact same thing (except you may just want to move your 4 or 5 buttons closer together or closer to the edge of the Pandora), except of course the strumming. In concept, both will require you to properly time your hitting of 4 or 5 keys in a row as the notes/arrows fall/rise to the appropriate zone on the screen. It seems like you could just take any old Stepmania clone and add a "Guitar Hero" plug in and get what you're after.