So I had the idea that if the world isn't entirely collapsed yet in 2364, there could be the equivalent to a Mega City One esque Cyberpunk metropolis. I'm thinking the Mega City could either be based in Detroit or maybe New York City.
A MegaCity type location would have had to deal with the Mecha virus somehow, or nearly all tech in the city would be slowly trying to kill people (or multiple strains of Mecha virus?).
A city like that would need some way to recycle wastes into useful materials, as well as scavenging any useful resources outside of its walls. This could be a clue to the characters, where they enter a region and there is no scrap anywhere for several dozen miles around them.
Airships might be a way to get to the city, if they can carry enough fuel to get from the edge of the scavenged zone to the city walls, trading for resources and enough fuel to get back to their trading post.
But a city like that would be an Outside Context Problem for everyone in TME. Here is a location with several hundred million people, decent tech, and mostly organized. This is a group that could dump that day's prisoners outside their walls, and those prisoners have enough manpower to form a nation to challenge anything the TME political bodies have.
(As a comparison, the United States has 655 people in jail for every 100,000 population. Assuming 400 million people in this MegaCity, that is ~2.6 million people in jail. Assuming only 1% of them might get sent into the wastes this way, that means annually this city would be dumping 26,000 prisoners into the wastes (~2000 per month!). Hope the cities in TME can handle groups like that suddenly arriving very year.
Now what you could do is run a group inside that city, never interacting with anyone outside. Resources are scarce because they have to be recycled. Food is basic, ratburgers are common. You have to scavenge for stuff to use as a weapon, and hopefully you can get enough education with a cast-off book. Damaged buildings can be explored for resources, while rival groups can be much closer due to buildings being closer together. Blockades are done by interdicting the nutrivend tanker trucks that deliver the nutritionally balanced slop everyone eats, while the city police crack down on any obvious threats.
It could be done, just remember that the scale will be different. An army of 5000 is enough to make TM cities band together to stop, while in MegaaCity an army of 5000 is a detachment from a Block War.
I was kinda thinking that the Humans and Mutants of this MegaCity would be stuck there and little if anyone gets in or leaves. For example they might have access to technology from the Humans who live in Orbit or on Solar Colonies, though that support would come rarely. Likewise the criminals would be locked up in massive complexes that are dedicated multi neighborhood areas. Also more often than not the Justice Bureau would just kill most criminals.