It would be nice something like a Guitar Hero/Rock Band clone. Rock Band 3 and Lego Rock Band on DS were pretty fun.
The feature that would make this really great was compatibility with Frets on Fire's songs, so it would already have a giant song list and plataforms for people to write their on songs. Of course this would demand a five lane game, opposing to the four line system of those DS games.
Other nice features would be customizable buttons (a .cfg could do the trick, I guess) and a simple high score system. I don't know if it's possible in homebrews, but maybe wireless multiplayer in the future? This last one would be very hard, I imagine, but just dreaming.
IMO there's no need worrying about star power, whammy, multipliers or nothing like that, even less background animations or crowd sound. Just a nice rhythm game
So, anyone think this would be possible? What do you think about this idea? If someone else like this please show support here, maybe we can grab a developer's attention.