Wow, amusingly, I was thinking of the possibilities of a rhythm-based RPG several years ago. It was actually kinda like this, except the player wouldn't have had to switch between three different panes in real-time. To be honest, I like your approach better. Very cool. I'd definitely like a copy.
By the way, I've noticed numerous developers/publishers giving away codes for games on Steam, and I'm curious as to whether or not there's a limit as to how many you can give away, as well as whether or not there's any cost to you by doing so. The reason I ask is because I'm interested in eventually developing game for distribution through Steam, and I'd like to know how Steam handles giveaways.