In my last dream, I was the member of a small human colony in a giant constructed place of some kind, building in all directions (if you've read the manga Blame!, somewhat like that, though not as vast-seeming), but very colorful, some bits almost like a playground. We knew our local area in every direction, down, up, and so on, and it was colorful building stuff everywhere, and that applied as far as we knew existed.
Open space was fairly common but not super large, and there was always more colorful building beyond. As we went further out our knowledge faded as territory got more dangerous, what we actually knew was fairly small, but there were plenty of other colonies of humans out there we knew, including ones beyond our reckoning of our 'known world.
We recycled or scrounged almost everything- including white clothing (most of our stuff was artificial stiff colorful material that was only good with overgarments, and even not-remotely-new white undergarments were valued. I had a few sets), cybernetics, which were our main means of defense. The communities leaders noted I had a high cybernetic compatibility rating and was talented so they were pushing me to get a full conversion, but I declined because I wanted to carry kids, which was an acceptable reason that was granted, though most other stuff was fairly strictly controlled, you only had so many points you could use for items and possessions were rare (my multiple-sets-of-cloths was wealth I was proud of, and someone with a cyborg eyebrow that let them light things up- not that things really got dark- was fairly well-off. Not that one could use cybernetic wealth well, but it was a sign of sacrificing for the community). Our leader was somewhat old and acted like they had founded the community, but we pointed out not only weren't they, but neither was the leader before them or the one before that, to which the leader would 'hrmph' and maybe say something about it being metaphorical in response to our ribbing. Though we didn't actually have much in the way of records, and all in all we were a fairly small group, and one of many human colonies who lived in the place and fought/hid there from the forces hunting us.
I went on a scavenging mission, and then I saw a battle between some of the forces that would hunt us some of the time- I'll call them 'Hunters,' (though I think my dream dubbed them 'Reapers.' That could've been an after-waking-up thought, though) I think they were machines or machine-plus-some-biologic hybrids, I don't think we were exactly sure what they were or their motives, but whatever they were, they came in a variety of shapes, and were dangerous- and Megas, the superhuman answer to them that were humanity's best fighting shot, who were stronger tougher and could fly. Which other colonies had, but ours didn't, and again, our colony of humans didn't know exactly what they were, but they were impressive.
Even the strongest Megas weren't a match for the strongest Hunter, though, as I watched a high-end Mega brush aside several smaller Hunter- the kind our Cyborgs could fight- to take on a 'Centaur,' the biggest class of known Hunter, to buy time for the rest of his people to get clear. The Mega was pound-for-pound stronger, but the Centaur was something like five times as tall and way more massive, and it was demonstrated that a top Mega could hold off even a mighty Centaur, something I had never seen before, but even then, couldn't win, as it took the Mega's hits and plowed into some of the terrain, breaking some of the building structure. The Mega wasn't out yet, but it was losing pretty badly when we decided we'd had enough watching and decided to bug out, and get back to scavenging and taking what we found back to the colony.
That's as far as my dream got, but I think it has setting potential.