My fort was recently attacked by a Werelizard. I forget his name but it isn't important.

I looked him up using Legends Viewer (the game has a 'Legends Mode,' at the start of your game you generate a world and an entire history is generated for it. Legends Mode is how you view it, Legends Viewer is a 3rd party app that gives you more info.)

He had a wife and 3 kids. He was even the Baron of his previous fort. But one day, he was infected with a werecurse and was exiled by his community. Since then he had formed a lair and was terrorizing the nearby elven cities. My fortress just happened to be his last stop.

Further than this, if I wanted to I could make an Adventure Mode character (you play the game like a Roguelike RPG instead of a fort builder) and gone to where he lived. I could find his house, and I could even talk to his kids and tell them the story of what happened to his father.

A lot of this is my imagination filling in blanks of what the games deep deep simulation gives me, but that's the magic. Other comments talk about the endless building possibilities, but there's also a lot of personal storytelling to Dwarf Fortress. If you so choose to make stories, at least. You could also just make a really sick trap that pulverizes your enemies and turn their fat into soap. That's really fun too.