Mods might be the best answer. Using commercial game engines to design an educaitonal game seems sensible. The likelihood that librarians or educators could create something comparable to the games students love to play is very slim. So, why not use a Mod (modification)? A colleague of mine has directed me to the game Neverwinter Nights. There are some current academic projects on the go using this game engine. See MIT & University of Wisconsin's "Revolution": http://gaming.mit.edu/revolution/ or read about the University of Minnesota's School of Journalism and Mass Communication's project.

If you're looking for a comprehensive overview of gaming and libraries, you must get a copy of the Sept/Oct issue of Library Technology Reports. In 9 chapters, Jenny Levine introduces the gaming generation, explores the cognitive processes involved in gaming, details how to set up games and tournaments in your library, and presents interesting case studies of how games are being used in public, school and academic libraries. This is a must read for anyone interested in gaming in libraries.
Levine, J. (2006). Gaming & libraries: Intersection of services. Library Technology Reports, 42(5)

If you've been working on developing a great game or are interested in discussing the gaming topic, a call has gone out for presenters for the next Gaming in Librabries Symposium:
http://www.techsource.ala.org/blog/2007/01/gaming-learning-and-libraries-symposium-call-for-presenters.html

Here is yet another library game using quiz-style questions. I haven't had a chance to play it yet, as they suggest it may take 45-60 minutes to play. From a peak at the review section, it looks as though they cover quite a lot of material for developing research skills.

Info Game: http://library.austincc.edu/help/infogame/start.htm