I've encountered something very weird---
A few years ago I played around with the settings in #Cadash in #MAME, I think it was the DIP switches, and I managed to unlock an entire alternate opening area.
I literally PLAYED this. At least one version of Cadash contains a complete different first level. It largely contains the obstacles from the normal first level, but they're in a different order. This alternate map connects with the normal first level at the first boss room, and from there the rest of the game continues normally.
I know it's there! I saw it! But now I can't figure out how I unlocked it in MAME! And I can't find anyone else on the internet who's discovered this.