I'll try to explain the appeal of that game, since I understand that it is not at all obvious. The game is very well fleshed out in it's details. Right now I'm making a fort dug deep into a mountain, and I've engineered control of a small underground river and used it to irrigate a large underground forest with giant woody mushrooms. I made a huge waterfall that flows right in front of my main dining hall that gives my dwarves happy thoughts when they walk by. The hall is fully engraved from top to bottom with depictions from the history of the world and the history of my fortress. If you look at the description of each engraving, sometimes it will be purely decorative, but it will often be something that really happened. Part of the charm of this game is the randomly generated nature of everything. For example, one of the engravings in my hall is a depiction of my master engraver engraving a masterwork engraving he engraved previously. I thought that was pretty funny.
All the sentient beings in the game have their own language, and names of places and people are randomly generated in those languages. It appears to make no sense at first, but you begin to accept it as part of the culture of the game. For example, the goblin civilization that keeps trying to invade my fort are called "The Rosy Flies", although I can't remember how to say it in goblin, something like Axpu Omgamuto or some crazy thing with alien forms of punctuation.
The combat system in this game is brutal. I'm not even sure it could be considered kid safe. No hitpoints here, all body parts and vital organs are accounted for, and if you lose an arm or a finger it's gone for good. Battlefields are stinking piles of blood, gore and vomit. Once when a human caravan was visiting my trade depot outside my gate, it was attacked by goblins. One of the human macemen hit a goblin so hard his arm flew up and hit my archers up on the fortress wall. When a wound causes bleeding, wherever that creature goes it will leave a blood trail. Sometimes your enemies will try to flee in this condition, but if you follow the blood trail you'll often find they eventually bled to death and you can take their stuff, or they might be lying on the ground unconscious. If you don't finish him off now, he might be back later but with more experience.
Even the bug reports for this game are fun. One person recently wrote that the human liason that visited his fort to discuss trade matters was missing a leg from some previous battle in world history. Every year he would enter the map and leave a shoe and a sock on the map edge, which he obviously was not able to use. This game has depth!
