One of my players knows exactly what Dwarf Fortress ( http://www.bay12games.com/dwarves/ ) is, and my Sunday campaign is sometimes referred to as "C&C: The Dwarven Fortress." I ought to explain the way that Dwarf Fortress has influenced my GMing style, and perhaps you may find it useful as well.
First, since this is a blog, I can rant as long as I want. Consequently, I shall now present a relatively brief history of my interactions with city-building games. I started with the SimCity series, the Civilization series and Colonization. I later discovered a rather addictive game by the name of Transport Tycoon ( http://www.youtube.com/watch?v=Gyw79aawqxo ), which is not as well-known - it is a game about building roads, railroads, seaports and airports, and micromanaging the vehicles and services provided through them. One SimCity clone which I was particularly fond of was Mobility, a German game about optimizing commute times and traffic safety. Sadly, Mobility does not contain highways or larger-scale railroads, making it unsuitable for the exploration of common transportation problems within the United States. One of my friends later introduced me to a game by the name of Emperor: Rise of the Middle Kingdom ( http://www.youtube.com/watch?v=0rwiKTrs6uc ), a very complex game which unfortunately does have a "correct" way of being played. In recent years, I mainly played Emperor and SimCity 4. I especially preferred the latter for its combination of breadth and depth while still not having a "correct" way of building a city.
Finally, I kept on hearing about a rather addicting game by the name of Dwarf Fortress. This game is astounding in both its breadth and depth, while still having a focus that prevents your ambitions from going a bit too out of control. The only way to truly get a sense of its features is to attempt to play the game. Since our free time is limited and the game's interface has a rather steep learning curve, I will try to summarize the features which may be useful for running a pen & paper game:
1. The terrain is generated somewhat realistically, and includes varying rainfall, temperature, aquifers, topology, soil type, rock type, proximity to a source of magma, swampiness and all sorts of other details which would be too difficult to consider without computer assistance. At the same time, this game is not an academically-rigorous modelling tool and instead divides its worlds into a hierarchy of squares, making it very convenient for getting an overall world map, then a detailed map of a region, then a very detailed map for combat or town planning. One thing which you might like to do is create a world in the game, then take screenshots of a world, then draw over them in order to create a very realistic and believable world map for your own game, all with minimum effort when compared to rolling on tables and what not. For my Sunday game, I did not use this exact method, but I did find that more-realistic worldbuilding was far easier after having learned it from a game, as opposed to learning it from a series of textbooks and lectures. After three Earth Science courses, I still did not know as much as this game taught me within only five minutes.
2. The game gives you a very good sense of the requirements for certain types of technology. Rather than artificially-impose "tech levels" or "research," the player is responsible for driving societal development. Most players typically go through a hunting & gathering phase, a subsistence farming phase, and a prosperous trading phase in which they finally have a stable output of metal tools. There is nothing in the game that forces you to go through these phases - rather, it is simply a consequence of what can be accomplished with your current population and resources. The game could be seen as a sort of test of Jared Diamond's theory that the progress of civilization is determined by resources, animals, weather, etc. This aspect of the game influenced my GMing style by forcing me to consider, "Who, why and how?" to whatever that is present in the game. Who made all of those magic items out there? How did they get scattered throughout the world? Why is this city here, and not ten miles down the road? Why are the orcs raiding this village? After such questions are sufficiently answered, I find that there is suddenly far less preparatory work to be done, as it makes it easier to improvise reasonable and logical consequences for player and NPC actions.
3. The game works on what seems to be a scale of either 5 feet or 10 feet for each square of game area. Conveniently, this roughly corresponds to the typical scales involved in dungeoneering. Simply by playing the game, you create a future dungeon or site of ruins. Each room already has a logical purpose, treasures are already strongly suggested to be existing in certain rooms, traps may even be pre-placed depending on how you play the game, and in some cases, the cause of abandonment of the place is provided. The only thing left for the GM or module writer is to place monsters, determine random encounters, and roll up treasure where it makes sense. For my Sunday game, I did not use this exact process, but did design the dungeon according to how I might have designed a fortress myself, and made sure that certain types of rooms were not too far from each other, so that it would be feasible for creatures to have lived in the place.
There are countless other distinguishing features of Dwarf Fortress which simply cannot be sufficiently explained in any blog, or even within a short book. However, I do hope I have successfully elaborated on how the game can expedite the process of learning about subject matter which is normally only found through enduring that painful institution known as school.
Why the emphasis on realism? This is because I am a computer scientist, one of my friends is an aerospace engineer, one of my roommates was a mechanical and electrical engineer, my father is a computer hardware designer, my brothers are computer programmers, and countless other people I know in real life are schoolteachers and technical folks of various sorts. We like things to be as rational as possible before intruding on the domain of magic and fantasy. For us, player skill means applying our real-world knowledge. I simply cannot be satisfied with an old-school style dungeon, in which rooms and hallways are placed by a disciple of chaos or an adherent of discordianism.
When running games for people such as these, especially for a gamer such as myself, it is insufficient to simply describe a room filled with random contents. If I know what the purpose of that room is and what the technological determinants in the area were, I suddenly have less work in describing the room. Instead of having to pre-write everything that could possibly be in the room, and having to say, "This is exactly what you see, and there is nothing else in the room besides what I say, whatsoever," I can simply begin to describe it and my players are able to figure out the rest using their player skills. I can then move on to describing the more interesting elements of the room quickly.
This runs into the whole debate about what the "old-school style" of play is. Considering the educational background of myself and the majority of the people I know, it may sometimes be a good thing when you do use abstraction and rely on the book's rules, rather than rely on player skill. One example is the second-most popular tool of adventurers, second only to the ten-foot pole: the burning oil. I describe it as something with a wick that you light on fire with a torch, and which then shatters on impact and spills its readily-burning oil onto the target. One of my players started asking me if it had phosphorous so that it could burn spontaneously, and I also pondered if it was perhaps kerosene or gasoline. My player then responded that it could not be gasoline, much less kerosene, as those require certain conditions to be ignited. He also thought hard about what sort of oil would completely burn away within 1d4 rounds. We decided to just drop the issue and rely on what the rules said about burning oil, since our player skills were clearly getting in the way of fun.