The megastructures are everywhere, but not truly omnipresent. Patches of organic life and raw earth remain; or perhaps were created, the chewed-up and redistributed detritus of the ever-shifting architecture. Other regions are so heavily developed that little of flesh and blood can survive in them without mechanical aid. Like an immense fungus spreading in one direction and decaying in another, each of those behemoths reshapes the world in its passing. But its body can be characterized by broad generalizations, as listed here.
Endless plains of plastcrete tiles, like scabs on the raw surface of the Megastructure. They are poor in biomass but rich in energy and raw materials, with settlements burrowed into them and half-merged into the endless stretch of weathered gray. Hardy bioforms and scavenger machines populate the floors, along with more dangerous organisms along the margins.
The wastes are areas abandoned even by the Megastructures, great plains of dust, rubble, and ruin. Life is hard here, but its isolation offers safety of a sort. Few travel into the wastes, so those who seek an isolated lifestyle often gravitate towards such places, keeping to themselves in quiet exile, until something greater than themselves makes a meal of them.
Dense, high-energy regions of the Megastructures deeply hostile to conventional organic life and crawling with machines and posthuman fauna, including hardlight organisms. Such places host a rich bounty of advanced materials, but accessing them without being consumed by nanomachine swarms or gunned down by feral drones make extraction difficult.
There are great mounds emerging from the surface of the megastructures, half-ruined cities of maddening architecture endlesly growing over themselves, like calluses on skin. These eternal ruins are said to echo the greatest civilizations of prior eras, witlessly echoed by some dim memory inside the ambient N-matter. Their proximity to space makes them frequent resting places for spaceborne machines and other void-dwellers. Those silent, swift enigmas make traversal dangerous, especially after dark. Those who are smart burrow into the ruins and hollow them out in imitation of the old arcology-cities, letting those voyagers have the surface to themselves.
The remnants of artificial organic biomes meant to aid in terraforming processes and sustain breathable atmospheres, allowing for organic humans to thrive with minimal life support. While found across the star system, only on the homeworld are they common enough that the air can be casually breathed, with no concern about straying to far from bubbles of oxygen-dense atmosphere or running out of air in your canisters. Furthermore, many host quasi-organic ecosystems almost like the ones from before the megastructures. Such oases of biomass offer refuge to the needy, and even the most primitive civilizations can survive here. But the richness of growths attracts greater powers, and so those who rely on its bounty alone rarely manage to protect it.
Places like the Floors or Wastes, but irregular and bulbous. Settlements built into such places seem half-devoured by the shifting architectural bulk, and countless dangers hide in the crevices and mounds which spread across its surface. While they are far easier to fortify, raiders proliferate in these regions, striking out from their hidden paths and vanishing back just as quickly.
Voids are places where the atmospheric regulators of the Megastructure have dwindled, becoming freezing cold deserts filled with engineered life forms bordering on alien and the posthuman monsters that hunt them. They offer little, save that some of the things that live here possess exceptionally high energy density, and can be harvested for their rich tissues and converted into vast stores of power.
Frozen-over runoff. Perhaps the most inhospitable environment that exists within the Megastructure. If you are looking for a place the world will ignore you, this is probably it. However, food is always an issue as the runoff makes any usage of microfactories or hydroponics nearly impossible. To dwell here is to live in subsistence, unless you burrow far below and hope its bleak surface wards off interlopers.
Small oases of drinkable water, often with engineered fauna seeded in by nomadic pastoralists on their long routes across the megastructures, or simply brought within by the underground pipes and resevoirs. Quality of the waters can vary widely depending on the pool’s location, and one can never be sure what is lurking in the depths.
Artificial seas spawned by ruptures in the underground storage systems of the megastructures, it is said that their waters are the same as the ones that once filled most of the homeworld, but swallowed up by the titanic machines that reshaped its crust, filled with pollutants and unknowable compounds, and vomited back onto the surface in unpredictable eruptions.
The inner world of the megastructures, divided between the barren, muddy pseudo-caverns where they retreat or grow into, and the developed regions where they exist in full. The former are desperate abysses primarily populated by organic or biomechanical life, and the latter are dominated by machines. Any who seek to fully utilize the bounty of the megastructures must venture into these depths, but the risks are great, and there is always the chance of unleashing things that cannot easily be sealed again.