Still, many academic researchers have high hopes for the potential uses of virtual worlds. Tim Lenoir, the Kimberly Jenkins chair for new technologies and society at Duke University, sees virtual worlds as powerful training tools. Lenoir is working on a world called Virtual Peace, intended to train people heading into difficult negotiation scenarios. For years, he says, the military and other organizations have used paper-based role-playing games for trainings. Virtual worlds are a natural step up from that, since they allow people to become more immersed in the scenario, and allow for richer background materials, he says.

And Nina Fefferman, an assistant research professor at Tufts University, recently published research on the Corrupted Blood plague, a virtual disease that spread through World of Warcraft in 2005. She believes that game scenarios such as this can provide certain insights into real-world epidemiology, and can be used to run experiments that would be impossible or unethical to run in any other way. "Insights from virtual worlds are like those gained from analyzing historical data," she says. Fefferman is currently speaking with game developers with the hope of continuing her study of virtual epidemics.

Castronova is still planning to pursue experiments in virtual worlds. Social sciences need to be able to do controlled experiments, such as those done in the natural sciences, he says, and virtual worlds could be a good venue for that. In order to use them credibly, Castronova says, scientists need to test how accepted theories hold in game worlds. Political scientists should set up experiments to confirm that people in games vote in tune with their interests; sociologists should set up experiments to confirm that people's relationship to conformity is similar; and economists should test the basic principles of supply and demand. "A virtual world is a tool like a petri dish," he says. "We need to find out what you can do with a petri dish, and what kinds of things need a live rabbit."

Castronova's next step is to rebuild Arden with an eye toward making it a place where players will want to be. "What we've really learned is, you've got to start with a game first," he says. "You just have to." The new version is titled Arden II: London Burning.