That’s not what “losing is fun” really means. Winning and losing in Dwarf Fortress is not like most other games. In most games, having everyone in your fortress die would be a loss, it wouldn’t be much fun, and you would have to start the level over. In Dwarf Fortress, by contrast, this can be counted as a win as long as there was a good story to it, or if you learned something new about the game.
I’ll give you an example of a fort that I lost. I had dug down into one of the cavern layers beneath the world and set up shop. I started walling off a good–sized area down there, making it safe from fliers and swimmers. I built walls across a lake that would keep them out but still let in fresh water, and hopefully cave fish. At the edge of the lake next to a courtyard surrounded by stalagmites I built a simple little well house to supply the fortress should the booze ever run out.
Naturally, all this activity attracted attention, and forgotten beasts attacked the fort. I had a rag–tag militia with whatever weapons I happened to have on hand and some armor go out and attack the first one just outside the walls, not far from the well house. They fought hard, and managed to take down the beast with only a few casualties, who were soon carried back to the hospital.
I then directed my butcher to carve up the carcass; this thing was huge and it would likely feed the entire fort for six months or more. He duly dragged the carcass past the well house, across the courtyard, into the stairwell, and up a few levels to the main body of the fortress.
All was going well a few months later when I noticed the blood.
There was blood in the hallways, and blood in the courtyard, and blood in the well house. There were dwarves running around cleaning the blood, but it never seemed to go away for long. You would expect there to be some blood after the fight, and there was. But even dragging the carcass of a huge forgotten beast wouldn’t leave a trail of blood down a hallway; in Dwarf Fortress a dead creature can no longer bleed. Even the meat you get from it doesn’t have blood in it any more. So where was it all coming from?
I inspected some bloody areas, and found that it was dwarf blood. Indeed, Dwarf Fortress keeps track of this because the details matter; for every contaminant that comes from a creature it knows _which_ creature it came from. It wasn’t just dwarf blood, it was blood from specific dwarves! I started looking through my dwarves to find the ones that were bleeding.
All of them had rotten feet.
The skin, fat, and muscle layers of their feet were all rotting. Everywhere they walked they were leaving bloody footprints and smears of blood. They would go to the well house and try to clean themselves. They would try to clean the floors, and get it on themselves again, and on the clean floors. Any dwarf that got that blood on their skin was getting some kind of infection (or “syndrome” as the game calls them) that caused their flesh to rot. Animals and pets had gotten it too. Cats follow their dwarves around, so they were stepping in the same pools of blood and had rotten flesh on their paws.
And that’s when I remembered, the description of the forgotten beast said that it had “poisoned blood”. Forgotten beasts are randomly generated. The game picks a body plan from all the creatures it knows about, randomly changes details such as material, size, and color, adds interesting features, and then sets them loose in the world to harass your fortresses. Poisoned blood is an especially interesting feature because the poison itself is randomized. The game generates a suite of randomized syndromes (on top of the non–randomized syndromes used by various venomous creatures, etc), then uses those syndromes in various nasty ways throughout the game. This syndrome apparently caused flesh to rot. When the forgotten beast bled from its wounds during the fight, it got on the ground and on the armor of the fighters. From there it spread, until it was everywhere.
I might have forgotten that beast’s randomly–generated name, but I’ll never forget the story. Thus I won, even though the fortress was lost.
In fact, the fun doesn’t necessarily stop when you lose a fortress, because you can always start another fortress in the same world. Since it’s the same world, it has the same threats. In particular, it has the same syndromes. There’s a good chance that any fortress in that world would see this kind of threat again, even if that one forgotten beast was dead. Hopefully I would have been able to deal with it better.