That game's too fast for me, but I've been wondering how well a "joy joy revolution" game would go over if it used my BTP2 (Better than Pitfall II) music (or maybe even a successor version BTP! (Better Than Pokey!) music).
yea, i was the only one of our team actually able to complete the game. i suppose you get a feeling for it after testing the synchronization ad infinitum. Kind of hits that super-niche market of stepmania-playing atari2600 owners.
As for your song, the ddr source code is in there and is pretty modular. the sound processing is pretty much the same as an example posted on one bB documentation page, "change note reg after x cycles", with a windowing function. Since the game draws arrows every 4 cycles, if you used the same method for sound playback, just make sure your durations are all multiples of 4 and start experimenting with step patterns. the only catch is that it the sound may break down or get weird volume control if you have a note duration less than 8 cycles (but id stick to 12).