What I'm curious though is about the Geoscape/Storyline of this Total Conversion. Lately I've been also getting very interested in developing TCs but this is a sort of project that I'd like to do together with someone else because of the work involved.
Geoscape modification is too far away in the future to be detailed now; I only have a rough idea. Storyline will be quite lax, I don't want to lock the player into a narrative; also I'm mostly set on the idea that every research should give the player something, so no "story researches"** (with the only exception being the alien life cycle).
**Not that I think they're necessarily bad, they're probably needed if you're aiming for a more flashed out/rich narrative.
I don't think anything in mapscript/mission script is yet fleshed out enough, but I'm hopeful that there will be some more options to do some interesting things with those once they are better documented. You can tie a race to a terrain now, so I wonder if there might be a way to hack that together with the civilians? I'd love to be able to do something like APOC defense stations, but there's just no way to do it right now.
About turrets, I asked Warboy on 0-energy HWPs too (I removed the defense facilities). The problem with that solution is that there's little to no control about their spawning on the map, since there's no HWP-specific spawn points.
About civilians in base, I guess another way to try to do it would be to turn the engineer/scientist items into HWPs. Provided it works, it would be fun to see what happen when a base with 100 scientists and 250 engineers is invaded