I remember going on my friends PC to play The Incredible Machine and finding this DOS Demo, it had 4 or 5 singing skulls on a black background with red eyes and fire mouths. Possible mid to late 1990's. I only have a sound recording from a cassette tape recorder of the PC playing the music. Here is a link to an MP3 of this music, I hope someone can help, this is one little thing I have never found out.
https://drive.google.com/open?id=0B2lne ... FVjTkhmV0U