Xen concept, help req.

Hi Twhl, i felt like posting this here would be appropriate since it's going to be related to HL (doh!). Anyway, i would like to get something cooking in UE4 - a multiplayer Xen level for the current UT prototype/future mod of UT. I will try to mod whatever i can, to give a bit of HL feel, after i'll sink my head more into scripting.
I know this part of HL didn't had many fans, but i've enjoyed it...somewhat.

Anyways, what i want right now is a solid starting point - reference and concept art! I browsed a few hours teh interwebz and I couldn't find anything solid. HL2 completely ditched it; Black Mesa Source has nothing available to put out publicly either.
Some stuff & pointers/ideas i got so far:

floating terrain.
minor vertical gameplay.
alien theme. Green, white-grey-black, orange? - thx H.R. Giger
heavily organic level.
organic matter should blend into world geometry. Ex: "lively" half plants-half rocks, animated protruding "tree roots".
lights coming from crystals/crystalytes/plants.
no obvious straight shaped geometry unless it's spikes.
abundance of beams & particle effects.
color changing slime/liquids?

That's pretty much what i got right now. Other than the above i don't know wtf to do. Any suggestions or reference photos?
Also, would it be ok to post some wips once i get things rolling? I know there's better places for UE stuff, but i'm mostly doing this to capture the feel of Xen on a modern engine.
P.S: I don't expect to finish it by the end of this year.

Some stuff from deviantart:

Xen concept, help req. Created 8 years ago2015-06-20 20:04:04 UTC by Renato