These novels have the particularity of being in the realm of the possible, so it's still considered science fiction. Many authors use this type of story to expose their vision of society, human nature, relationships between people, the future that awaits us, etc.
For the actual catastrophic event, viruses seem to have supplanted nuclear explosions (in addition, viruses bring less damage to the landscape and allow the survivors to return to an idyllic nature).
For dystopias, no surprise, oppressive societies abound, mostly of the totalitarian type. In fact, one often wonders how they survive, as no one seems to produce basic things like food, clothes, paper or microchips or mining and processing metal. A view typical for the western urban author for whom these things magically appear at the local supermarket.
“An epidemic has just destroyed the entire world population, some survivorsa re trying to rebuild everything.”
If you go to an online English-speaking Speculative fiction bookstore, you will see competing dozens of books on that theme. Most attract the same criticism. I won’t dwell on the fact that all these stories take place in the US and that the first reaction of the survivors seems to be to kill each other. If you want to escape the clichés, here are a few remarks.
- If you lose in the space of a few weeks / days / hours / minutes your family, your friends, your job, your livelihood and in general everything that makes your life, it will take you years to recover. Ask a survivor of any war, there is no shortage at the moment. No, you won't be looking for a girlfriend right away if yours died six months ago in excruciating pain. You might be looking for moral support, but it's not the same kind of feeling. In short, your optimistic hero, full of energy and cracking joke might need a revew. Otherwise, choose a hero who was marginalized and socially disenfranchised before the catastrophe.
- Find out a minimum about the infrastructures in the country where your story takes place: electricity (by the way, do nuclear power plants really manage to shut down on their own, if there is no longer any technician?), gas, phone, water, food, germs, rats... and did you know that gasoline breaks down over the months? What about batteries? Ammunition supplies?
- Paradoxically, in many postapocalyptic novels, the heroes are always in search of food, but never of drinking water. Imagine what would happen in a matter of days if there was no more tap water in a big city!
- The people who are most likely to survive a planetary epidemic are not those who live in a large city, but in an isolated village with little contact with the outside world: a religious cult, an Inuit village, the inhabitants of a small Pacific island... And if you are a group of pygmy hunter-gatherers deep in the Congo forest, do you need electricity or gas as much as a westerner? In short, you can seriously review your plot: the future of Humankind will not be assured by white, educated and idealistic New Yorkers, but by a bunch of villagers from the back of beyond.
- Finally, your small group of survivors generally has one woman, at most two. How many children do you think they will manage to have to ensure the next generation?
“In a futuristic society, large multinationals companies dominate the world and the majority of the population lives in poverty. The middle classes have disappeared.”
- First, you have to decide whether there is still competition between companies or not. Is there a black market or a parallel economy? If yes, what’s its size?
- Most importantly, do you really need a pair of brand X sneakers? The last Y cell phone? Z handbag? If you barely have enough to buy food, do you think you'll always be interested in them? So if the population lives in real poverty, who is going to buy these products and bring profits to these companies? A small elite? Your multinationals will have to undergo a hell of a slimming cure. It would be a return to the economy of the first half of the 19th century. Nothing new.
- Now imagine that your big company doesn't make such trivial things as fancy sneakers, but has a monopoly on something really vital, say water or oxygen (like in the first version of the movie "Total Recall") or a pollution control system, a source of energy, of food ... There, you have a really interesting situation...
- Finally, imagine that your company has a monopoly on something which is not vital, but is perceived as such by the population: for example a drug that allows you to stay euphoric even when you are in dire poverty!
In short, if s/he imagines the hungry poor buying the latest sneakers, it's because the author is him/herself conditioned by our society of abundance.
So if you embark on this kind of dystopia, you will have to learn a minimum about the functioning of an economy / society (yes, more homework!) and use your common sense.
“A futuristic society where a small elite lives in luxury, while the rest live in a polluted megalopolis, in conditions similar to the Middle Ages.”
Another fashionable cliché, which mirros various current social debates.
At the start of the 21st century, we are seriously discussing the basics of our daily lives: where does our food come from? Our electricity? Our fuel? So can you imagine a futuristic society without asking yourself these questions?
In your dystopia, where does the food come from? who works the fields? Why would a poor person live in a big polluted city, crammed with crime and drugs? Wouldn't it be more interesting for him/her to leave the metropolis and cultivate a piece of land in the countryside? If the answer is "no", why?
Back in the 20th century, we imagined the oppressed masses forced to toil in factories for the elites. Right now, it is rather the opposite: we imagine that these oppressed masses will be unemployed. Then, you will not escape socio-economic discussions: does your society have a market economy? If so, who is buying what and at what price? Only the elites? Have robots replaced humans? And if so, wouldn't a desperate unemployed person cost less than a robot, after all?
If your elites are truly all-powerful and evil, why are they tolerating all these poors? Why haven't they already wiped them out with some mass destruction technique?
By the way, if your poors really live like in the Middle Ages, the problem of overpopulation will very quickly be resolved "naturally" by some epidemics and famines! Besides, have you ever tried estimating the number of individuals in your dystopian society?
In addition, the reaction of the poors in this kind of novel is far too similar to that of the idea we have of the poors in a modern Western country: despair or indignation. These persons would spend their days lamenting or being angry.
However, someone who would have lived in these conditions for several generations, would consider them as normal. S/he wouldn't spend his/her time complaining and would even occasionally be happy and laugh. People who really live in the slums of the Third World don't spend their days complaining, they are too busy working, looking for work, taking care of their family, or even chatting with friends!
This also means it will be much more difficult than you think to get them to rebel in a "constructive" way (how long did it take to get from an absolute monarchy to a republic in France?).