I once found a the data disk creation program somewhere on the net (I'm not the author). Apparently I forwarded it to Sean; it's too long ago for me to remember. But I think it just reads some garbage data that someone mistook for a stage. When I tried it, it didn't look anything like the stage in the first link.
I remember loading the "special stage" but it looked like the "caverns" that are behind Benson's picture. That's why I got surprised seeing the screenshots of www.sdsnatcher.net.
