seems i can throw these together rather quickly and easily,
(this isn't finished BTW)

The main problem i may run in to is that once finished, they can take DAYS or even WEEKS to render on my current computer system.
this unfinished work alone took a good 4 hours. (I think it was the application of a light source in the volcano)

Not sure if that kind of thing would work out as an overworld for anything that wasn't Super Mario RPG styled as far as the gameplay went.

That lava makes me think of Lava Reef for some reason. Not for the fact that it's lava, but the look of the lava itself.

Dont forget that donkey kong country did the same thing,

and really, this would play a minimum roll in gameplay, since it would act about the same as the overworld in SMW. playing the roll of a level select, and nothing more.

Good point.

I'm attempting to imagine how something would look if this were done for Twisted Dream. I see cool things.