After huge quantities of pollution, melted polar caps, and one super volcano eruption, some countries made different bio domes to protect their cities, and some have even made them mobile to salvage what's left of their polluted world.
The dome, Chrome Regios, was a giant terraformer trying to clean and refresh the world. One of the scientists working to this goal thought of an idea to allow people to survive outside of the dome and tried to create a serum that caused people to adapt to the environment and survive in such a harsh climate. While the serum didn't work, it was mass produced for the abilities that manifested from it, such as psychic abilities, regeneration, and many more, but the serum wasn't without side effects. In 10% of the population it caused mutations in genetic patterns, and when the AI of the control tower of the dome scanned these groups, it deemed it a contamination and locked down the entire control tower, as well as shutting off the main reactor.
The state-sized city is having to rely on the animals and plants they brought with them since, due to the lockdown and subsequent power outage, they were cut off from the digging and salvage unit under the city. Although they can survive indefinitely, they can no longer move and have lost power from the fusion reactors, leaving the cities decrepit and barren.
Still, they aren't totally without power. There is a separate reactor for the Artificial Suns (AS), which balance the environment and keeps mass death from occurring. There are systems to each AS that, once all six are accessed (one in each district), could reset the bio scanners, which would then allow access to the control tower. However, with the power suddenly switched off, certain factions have come to prevent access to them.
((No, this picture doesn't fit. It would have to go all the way to the top of the dome and it doesn't have 6 different terrains around it. It's just a filler.))
