Limelight mode.
During this mode, the entire playfield is illuminated by lime green LEDs and you complete a series of targets (or rollovers) to complete the "Universal Dream." (10 Billion points or some such)
Truth be told, though - I am MORE on the bandwagon with those seeking a non-music theme for the next year or maybe 2. AC/DC and Metallica have sated that need for now.