The developer Nicholas posted this:
When I first made Synthesia, I left it kind of open which direction it could go -- more accessible/arcade-gamey or more realistic/learning-tool.
As time has gone on, it feels like the crazy majority of the user feedback has been on providing a tool to help learn how to play the piano.
That said, you may be looking for Keyboardmania. There is a PC version with lots of hip-hop and R&B type songs with original backing MP3 tracks. A pretty large community behind it from what I understand, too. (It's originally a Japanese game, hence the Anime music in that video.)
Keyboardmania, looks pretty cool and is dam close to what I was talking about, but it is missing the frets on fire cool factor (guitar, drums and bass, coops, multiplayer, etc) and is only for keyboards but it seems to be on the right track, if only it had the notes coming at you instead of down the screen, it would be right on.
I searched it in google and it seems to be a japanese playstation game based on a coin operated video game from japan and there is also a piano hero game but couldnt find that download either. there is a wiki page for keyboardmania: http://en.wikipedia.org/wiki/Keyboardmania
