There is a sub-genre that is fairly common to many gamers, casual and mainstream, that is the Life Simulation MMORPG. These are MMO's, like second life, WURM and even ATITD that attempt to simulate real life instead of a fantasy setting. Now when I say real life I don't neccesarily mean on earth (as WURM takes place in a fantasy realm but has the player deal with real life problems like food and shelter).
These MMO's for some reason have a great popularity, and I think I understand why. We, as gamers, play games to experience things we would not otherwise be able to experience, whether this is racing in a Nascar race or fighting an ongoing war between orcs and humans. It would logically seem that the tasks of cooking food and cleaning the house are uninteresting, but games like the Sims have made it clear that they are indeed fun...somewhat. Life Simulation is all about the what ifs...what if i became an astronaut instead of an English Professor. What if I decided to hook up with every girl I met? What if I had to live on my own in a shack I built myself and survive.
As aptly named as the game by the title is, these games give people a second life. Not just an entertaining character to play. People enjoy alternatives without all the penalties of those choices. Lets face it, our current life choices are permanent for the most part. We can't have all the options we can make in video games. That's the point, and why we buy and play so many of them. Lets face it, I'm an alt-oholic. I need to experience as much of a game as possible with many multiple characters, experimenting and trying other things and tactics, which is one of the reasons I liked Star Wars Galaxies and its skill system.
What I'm trying to say is that Life Simulations of any level are interesting because they simulate life. There's a large market niche here, but the difficulty curve can't be too high. More on this later, once I get a little more coherent on my thoughts about it.