When it comes to segments, to me variation is key. The idea of a crawling space above or below is absolutely cool, that should definitely be added in my mind. It needs to seamlessly fit in with the other segments of course. Which means there has to be a segment that offers the entrance/exit as well. For the floor it could be as simple as the same design of the standard segments except a floor panel has been removed and put the side, for example.
I don't think anything needs to be changed, only added to. Variations of the same kind of segment that come to mind are:
-some walls have panels, scifi-ish things
-arch's or miscellaneous designs that cover walls, maybe two segments across?
-different pipe layouts (cross over, some go up/down/into the wall)
-different floor textures (scratched up, messy)
-maintenance types (eg. floor panel removed, maintenance styled designs)
Also vertical areas are cool to think about as well. Its scifi, does everything have to be flat?
Just some thoughts from my opinion. Also, will you be releasing this media once its finished? I'm very interested in it.
Thanks,
Burger

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