SimTunes

[Wikipedia: http://en.wikipedia.org/wiki/SimTunes]

SimTunes is a children's software toy designed by Toshio Iwai and released by Maxis in 1996. It involves painting a picture with dots (large pixels), where each color (unless it was part of the backdrop, which was black or a bitmap) represents a musical note. The player places up to four different-coloured Bugz, which represent instruments or vocal syllables, on this picture, and can change their starting directions and relative speeds. The Bugz crawl over the picture, playing notes corresponding with the colours, and turning, moving randomly or jumping in response to function symbols that can be added to the dots.