Hehe, a rather cool musical game, "Synthesia".

Several years ago the author received a "cease and desist" from Activision and had to change the name from "Piano Hero" to it's current name, "Synthesia" <grin>.

Web site -> http://www.synthesiagame.com
Download -> http://www.synthesiagame.com/getTheGame.aspx
Online scoreboard -> http://www.synthesiagame.com/scoreboard.aspx
Video trailer -> http://www.youtube.com/watch?v=DdpsPM5fyNk
Other related YouTube videos -> http://www.youtube.com/results?search_query=Synthesia