It’s one of my favorite Dwarf Fortress stories! Though my actual favorite would probably be the tale of the catsplosion, which shows how interactions between complex systems can break things in unexpected ways.

Basically, dwarves in the game have infamously short tempers, and when their mood gets low enough they have a mental break and rage and break stuff, which tends to upset other dwarves, starting what is known as a tantrum spiral. These are often run-ending.

One thing that helps keep a dwarf calm is having a pet, of which there are many types to choose from. Cats in particular are popular since they clean up vermin, preventing the bad thoughts caused by their presence.

Cats also have one other unique mechanic, though. Instead of a dwarf adopting them like with normal pets, cats choose a dwarf at random and “adopt” them, becoming their pet.

Now here’s where things get messy. Animals can breed in Dwarf Fortress, and the normal way to keep their numbers down is to set excess unowned pets to be butchered. Except you can’t stop a cat from becoming a pet, and killing a pet causes a huge morale drop in its owner (often enough to cause a tantrum on its own).

So, onto the catsplosion: if you have at least two opposite sex cats, they’ll breed and grow in number exponentially with no way to get rid of them, filling your fortress until your CPU can’t handle the strain and your framerate slows to a crawl. This was the death of many a fortress back in the day until it got fixed.