This is part of the speculative worlds thingie. If you haven't read this link, do so now.
I was in a bookstore not long ago, in the science fiction section, looking at books. One talked about a city which was actually two overlapping cities that didn't interact. I thought "oh, interesting! Is it because of AR or..."
As you may have guessed if you've read a lot of books recently, it was nothing of the sort. It was a misfiled fantasy novel.
But it got me thinking about the idea in science fiction terms. The idea of a city where the classes don't interact. Hardly an original idea, but what if we approached it from the perspective of a technology which creates or forces this situation, rather than a situation where there is a hierarchy of classes that ignore each other. I guess you could call it "the filter bubble city".
Two things are necessary to see this city. First, widely available augmented reality - some people have it in their eyes, some people wear contacts or glasses, a few people are still holding up their eCellophane tablets and squinting through them.
Second, a reason for the population to have drifted into different layers. In this case I will be presuming that the economy as it stands today has vanished, and instead there are multiple economies in operation, each of which uses very distinct kinds of policies and practices, and each of which has serious technical and cultural barriers from trading with the others.
As you might guess, that second thing is the meat of the speculation. The first thing just enables us to frame and explain it.
We can introduce the fundamentals pretty easily: a main character is not wearing his AR glasses at the moment. The reason can be whatever plays into the plot, but the point is that without the AR glasses on, the city looks pretty much like any other city: storefronts, ads, cars sliding by.
When the main character puts his glasses on, all the ads vanish, digitally erased from the world, replaced by what the view would be if they weren't there. Similarly, names and icons float above people's heads, and the car-filled street is suddenly awash with red, yellow, blue - denoting safer and more dangerous areas to stand. The cars are also labeled - owner, destination, whether driven or automatic...
The point of this is to show how strongly his world is altered by AR. This becomes the basis for the way the different economies can ignore each other while literally occupying the same space. As the story or game progresses, it is possible to see the world through other people's AR, and most of them have the people who aren't members of their economy grayed out, and the people who are members of their economy are "painted". For example, the "digital collective" economy that runs almost entirely off of minifacturing and local hydroponics actually puts digital tattoos on their members, representing their specialties and standing. These are clearly visible on the outer layer of clothing, since they are digitally applied, not actually on the skin.
The main character is a "biotracker": his job is to monitor the ebb and flow of disease, pollution, and other health risks, as well as discover and counter any new diseases which emerge. As such, he is truly a local. To him, it doesn't much matter which economy a person is part of, they are still a disease vector. He actually gets paid piecemeal from each economy as he renders service, which, as he notes, makes taxes a real bitch. He could get paid in government scrip if he preferred, but he points out that getting paid by individuals in proxy (direct deduction from their owed taxes) is more valuable, since scrip is largely worthless.
The story is largely about his efforts to track and contain a new disease, which is difficult to track but not terribly serious. It's called the "tattoo bug" because its main effect is to create complex, almost mathematical depigmented shapes on your skin. It doesn't appear to spread from person to person, so he's searching for the vector and the source.
His tour takes him through most of the economies, allowing the audience to see each in turn, how it works, what it likes and dislikes, what sort of people it creates... and most importantly, the way it sees the city. It allows us to explore new ideas for economies, including how the economy will interact with foreign powers - in this case, the foreign powers share the same physical space!
We can also see how they treat research, development, intellectual property, personal rights... including all the ways they "break" traditional economies by having excessive computation and high-tech automation. For example, the "panhuman" economy relies heavily on continually and automatically renegotiated relationships. That is, when you wake up today you may find you are dating someone you've never met, but you can feel comfortable with that fact because your outboard brain knows you and your wants pretty well. Trying to ask a panhuman who they slept with a month ago when the tattoo bug first manifested for them... well, it's not as straightforward as you might think.
It also allows us to see how completely the economies and populations can self-segregate. The people on the street that aren't your people don't matter - you walk by them every day without even seeing them. But that can break down, such as in the case of a man who kept downrating a dangerous bicyclist from a different economy, only for the two to end up dating.
We explore the edge cases where the economies might have to bow to the greater good, even if it goes against their ideology. Comparisons can be made to class, but in honesty it's probably more like religious barriers.
Anyway, each economy appears to be a victim, rather than a source, and the disease is mostly an opportunity to explore how the world might be able to keep running even in a fractured and chaotic space where people can manufacture new diseases in their basement and the concept of 'money' has largely broken down.
As such, the plot of the book or game is really second fiddle to the excuse to try to explore exactly how something like, say, the panhuman economy would work. When people get seriously involved, maybe the automated negotiation keeps them together... but what happens if you wake up and find it's been negotiated away? Is it because your relationship was at its end... or was it just a blurp in the algorithm? What do you do in such a situation?
Fun questions, and a light exploration of some of the more obvious points that might arise in such a setting.