I just read a really good article from the University of Alabama on how they used social media sites like Facebook, Twitter, and blogs to create an alternate reality game that would require players to use the library resources. The citation is:
Battles, J., Glenn, V., & Shedd, L. (2011). Rethinking the library game: Creating an alternate reality with social media. Journal of Web Librarianship, 5(2), 114-131.
These people really did their research before designing their game and their assessment felt honest (a few articles I have read included more enthusiasm by the authors than the project seemed to merit). I hope they continue to do such projects. It sounds fascinating and I'm glad they shared their experiences with us.