I am currently working on my diploma project and I would appreciate any help you fine gentlemen are willing to offer.

I am trying to explain the success of Microsoft's XBOX Live's Achievement System by utilizing various psychological theories. (mainly the "Goal-Theory" and the "Self-determination Theory")

I am lacking some kind of evidence for the actual success of Microsoft's System. Even though it gets a lot of praise in the press, I have trouble finding in-depth papers or business reports to strenghten this point.

If you know of other scientific attempts to explain how achievement-systems / trophy-systems work and why they are so effective, I would really appreciate any information you could spare.

Thank you!

Moved to The Business, but this kind of data may be hard or impossible to find or even quantify.