So I have a relatively new adventurer who just snuck all the way north to a town that was a couple day's travel away. As I was approaching the place, the framerate steadily dropped to something like one frame every two seconds. Now, I'm used to running 200-dorf fortresses at 80 FPS on this machine, so if the framerate is that low, I know something has gone seriously wrong with the world, like the floor of the magma sea being mostly absent or something. Went to fast travel mode and then popped out in the town's market, and got spammed by several screens full of combat announcements. After the confusion wore off, I realized that half the people in the marketplace were zombies, and there was a giant battle royale taking place.
My adventurer is a custom race that can vanish from sight every so often, so I did that and ran around trying to help the living fend off the dead. There ended up being something like ten survivors out of what must have been at least 50 combatants. I couldn't find anything out about why this had happened, though there was a necromancer tower along the road about a day's travel to the south, so I suspected one of them might have made himself lord of the town. I stormed the castle, only to find that everything in there was Perfectly Normal. Just an axeman and a lord sitting around. Axeman asked me to take him on a perilous adventure, and while I wanted to ask him if he was aware that the End of Days was in progress just outside, I settled for merely taking him with me.
Thing is, I have no idea what is going on here or if there's anything permanent I can do about it. How does one tell what's happening in cases like this? I didn't notice any evil clouds or weather, or any sign that the town is in an evil biome.