Are there any examples or case studies of social games, specifically on Facebook, where the developer has made drastic changes to the economy? I'm specifically interested in examples where the old economy was based off of purchasing items with Facebook credits then moving to a new model where the same inventory or similar inventory is sold with a soft currency. The closest comparisons I've been able to find so far are looking at iOS games that have gone from purchase models to freemium models, but haven't found a comparable scenario in a social game besides larger scale MMO's.