Every now and then a convergence happens meaning that a world gets fucking destroyed. To secure their survival the inhabitants can either enter a combat tournament in sort of a creepy tower or they end up chosen randomly with odds 1 to 10 000.
With every convergence the Dim World expands to house the new folks. The Dim World is just a mesh up of all the realms that got destroyed, there are all kinds of parts, biomes, dimensions and shit. And once you get through the convergence you get fucking awesome upgrades to make you ready for battle. Except for everything being fucked up there are really no wars, people have managed to make more or less working societies so all the factions are not doing so bad.
Really the last big fuck up was caused by this cyborg dude, friends called him Skive for short. He was like super powerful even before the convergence when it was normal for people to be just fucking normal. Well, he ended up being able to just build into himself basically any ability that he could understand so naturally he was stockpiling everything he came in contact with. I am talking thermokinesis, I am talking time freezing, teleportation, object creation, invisibility, psychic powers, immunities to anything imaginable… and when I say thermokinesis I don't mean just for your fucking popcorn I mean making the stars go dark level of shit. And when some power was not compatible with what he currently had he just put it into another of his bodies - he had fuckton of them and called them puppets.
This dude he was all about protecting life and intelligence. And one of the things he wanted to do was to bring his old world back. He actually had a copy of the planet stored in one of his created dimensions frozen in time. The whole thing was cracked, covered in storms of phosphorus shards, the elements went insane. At this point the souls of his people were unrecognizable, the state they were in would make a great nightmare fuel, just fucking creepy. But our pal Skive believed that he could find a way to restore them. So he went to this place called Somnumheim to research local nightmare fuel fuck up souls. Somnumheim was literally on the edge of reality, like on the list of places not to go this is the number one. There is no way to move heat, light does not spread and all things that are not of the fucked up nightmare creatures naturally deaccelerate.
After some disagreements with few government representatives that went with him on the trip Skivernat eventually got the information and tools he needed. But he also needed to make sure that all 11 members of the expedition would get out of there. So he made a deal with a local demon to sacrifice all of his power cause demons get like exp for this kind of shit. Got basically reduced to a human which was even worse for him since he was a buffed cyborg even before the convergence. But they got teleported to a place just a few kilometers away from the border.
As soon as they got out Skive had a huge fucking target on his back. He had pissed many people in the past. So the first ones to arrive were the guys he copied time freezing from – cause they were from a super advanced galactic society for which this power was a part of their religion. Meaning it was unacceptable for Skive to have it.
When they unfroze him two weeks later in a holding cell to interrogate him it was already too late. See, their ability to freeze time was a bit special. They could stop objects from moving and return them to that movement just as one would expect to. But they also had the ability to move among these frozen object without adding an insane amount of energy to them. They would also sustain the same level of gravity for themselves and generate temporarily existing unfrozen photons so they could maintain visibility. It's basically the same kind of dreamy BS you would get in 90's fiction about this power.
Back to Skive though. He was not only debuffed he was also beaten up pretty bad just from the time it took him to get from the portal to the border. A few bones broken, blood everywhere, internal organs better not to count. But most importantly he brought with himself a … surprise, surprise … deadly virus. Multiple people have touched him during the transport and they weren't even fucking concerned about treating his wounds so nobody knew he was sick. I mean, nobody knew he was infective. Once they unfroze him they also unfroze the virus in the newly infected people and everything went to shit. Let's call the virus puffer fish.
Now, when you are frozen in a hermetically sealed room with puffer fish the puffer fish is frozen too making you completely safe. And that was Skives situation as he was being unfrozen only for short periods of time each day for interrogations. Long incubation time, no symptoms, puffer fish is everything a genocidal maniac could wish for.
Mayhem, things burning, anarchy, violence, a civilization has collapsed. Most of the population froze themselves in their temples hoping help would come from outside. Others took shelters underground not accepting defeat.
Decades of quarantine followed until the cure was discovered. The drone footage made it clear. Freezing yourself for years without freezing the puffer fish in the air around your body… let's just say that the temples are a terrifying look.