As far as my father is concerned Dancing Demon was a wonderful
innovation. For every computer I got after that he would ask "does it
have Dancing Demon?" and I had to disappoint him. If anyone knows of a
version for Windows (preferably complete with block graphics) I'm sure
he would be grateful!
Can't you run the roiginal under one of the TRS-80 emulators ? (having
got a real TRS-80, and no PC capable of running the emulator, I've not
investigated this). I would assume said emulators support sound out via
the cassette port (if you see what I mean), Dancing Demo was far from the
only program to use this.
-tony