I really like the concept of a music/puzzler amalgamation.
Also, the BPM alterations and beat creation is very impressive.
Sorry, I'm new, just wanted to gush some praise on this sucker. Now onto my suggestion.
I was wondering if you think it would be a good idea to make a mode so we could apply a key to each column (up to 5. 7 would be ideal), and push the respective key each time a block hits an area on the bottom. Bad description, but if you've played beatmania you'd know what I mean.
In any case, I'm sad that the beta is over. Busy days have only allowed me to try roughly 3/4 songs on the game.
Great job, in any case. I'd pay 30/40 bucks for the effort.