We seem to take it for granted that after the apocalypse everything will be bad. Not just a little bad, or bad-but-recovering, but eternally bad. But is that actually a reasonable assumption? Humanity recovered from being killed down to a few thousand people. Earth has been repeated blown up, burned, and suffocated, the latter happening in multiple ways depending on what life was used to breathing at the time. To get sustained terribleness we don't need a one-off event, but instead a Sustained Terribleness Continuation Plan, or STCP, which is impossible to pronounce and redundant. What is the STCP? Us. People are the thing that keeps everything terrible after our initial effort.
Once upon a time a few technicians were given a task that they weren't trained for, using equipment that was poorly-designed, and as a result, Ukraine has a big ol' Zone of Exclusion around Chernobyl. A meltdown led to a steam explosion, which blasted a whole lot of radioactive mess all over the place. The disaster was of such a large scale that the USSR had to stop pretending that it hadn't happened, evacuating the shiny new city of Pripyat and leaving it all to nature. After some initial "all the trees died" problems, nature rebounded, since a lot of radiation is hardly as dangerous as humans.
Combining the story "
Roadside Picnic" and the Zone of Exclusion yielded the strange game series STALKER. In it there are all manner of dangers. Some comes from the radiation scattered by the explosion and cleanup operations. Much more comes from the results of an experiment. I won't give it all away, but the general result was another explosion that twisted the laws of physics and created all manner of dangerous mutants. In fact, the bit of radiation and packs of stray dogs are the least of the worries.
People and their experiments are the big problem. To cover up the experiments, they created a fake religion, luring people in with promises of wealth, eternal life, or at least something better than living in an irradiated wasteland. They deliver on none of these, instead brainwashing them to shoot at anyone who tries to figure out what is happening. And then the hero shoots his way in, killing everyone, and possibly destabilizing the area even more, which makes the apocalyptic explosions a daily occurrence. The local apocalypse ruined the world, but we kept it ruined.
If you combine 50's nostalgia with 50's fear of dying in a nuclear war and thrown in an unhealthy dose of a timeless disregard for basic safety or environmental protection, then you get the world of Fallout. There was a nuclear war with China and now everything has been nuked except for Vegas. There are some mutants, mostly of the "radiation makes things bigger" variety, along with some people who turned into ghouls (zombies) from high doses of radiation. Some have human minds, some are feral. It's a bad world.
After so long much of the radiation would have dispersed. Animals and feral ghouls are susceptible to guns. The real dangers, the real problems, came from people. Some became raiders and drug dealers. Others joined the Enclave, which are effectively technologically advanced American Nazis who cannot merely isolate themselves to sustain their 'pure' form of humanity, but must also kill everyone else. That's right, while humanity is right back to the "few thousand people left" stage, these guys decide they need to weed out the undesirables. This becomes a plot point, surprisingly. New Vegas introduced Ceasar's Legion as a technology-hating slave army dedicated to conquering everything, which was also incapable of actually managing an economy or doing much of anything besides fighting. Raiders seem almost reasonable in comparison, since they sometimes recognize that if they kill everyone there won't be any more people to rob.
Worst of all were the vaults that the people designed. They all worked. Some worked to preserve human life, saving thousands of lives. Many more worked to drive them insane in new and creative ways. One was split down the middle to test paranoia. Another was designed to let in radiation, creating hundreds of ghouls. More than a hundred were built and less than two dozen were intended to just save people without subjecting them to extra torture.
I'd mentioned environmental protection and basic safety, so here goes. The background radiation, while an issue, would have fallen dramatically. Only a few locations are still heavily irradiated due to the bombs themselves. Many more are irradiated because of poor storage of nuclear waste. Leaky steel barrels dot the landscape, fallen out of trucks, dumped all over, contaminating the water and soil. In Fallout: New Vegas there is a little exhibit about these that uses absolutely no subtlety to show the exceptional lack of attention to, or regard, for safety.
The cars appear to run on nuclear power, and take barely more than a nudge to explode, often triggering chain reactions. One might even wonder if the bombs ever needed to fall, if a few car crashes might have done the trick. And of course players might find that these little nuclear bombs are handy improvised weapons, so it's not as if we're the sparkling heroes of humanity.
Certainly both of these worlds suffered from human-caused nuclear disasters, but it was their actions leading up to and in response to the disasters that created the long-term problems. Crises are momentary, but human nature and the resulting messes, are nearly-eternal.
