My favorite thing here is the sheer absurdity of how complex it is. Sure, a lot of stuff isn't shown, but the fact that this game simulates hundreds of years of cultural development, war, myth, and even god damn erosion before even receiving player input (aside from the different starting parameters but that's kinda an aside). You could open a book and find out "Oh! Lord Asshole of Totalshitole was slain by Brandy Beard the Drunk 237 years ago! Neat!" and that will have actually been a thing that was generated. Not just the game deciding "Ok, I'll have a person die now" or "Ok, we gotta make something to fill this spot in." The game straight up every variable to come to the conclusion that this would be the outcome due to prior events; and that is STILL true, even if you never pick up that book in the first place. Lord Asshole lived, and died, to bring the world to the point it is today.
I find that comforting in a way, because at the end of the day, that's kind of true of us as well. Sure, life is far more (possibly infinitely so) complex than this game, but at the end of the day, we still exist, and even when we die, we still will, regardless of whether we get a book.
I didn't mean to get all philosophical there, but ah well. I still think it's nice.
Insert some shitty meme here for ironic effect.
EDIT: I just remembered that I once noticed a random goblin in my fort, got really nervous (I didn't have any military at the time), only to realize that he was the Outpost Liaison; I don't know what he did to get a Dwarven Civ to trust him so much, but that is the one goblin I couldn't kill. Crazy how you can still be surprised by this game in such ways.