After graduation, my friend and I decided to build mobile games instead of finding jobs. Today we released our first game called Monster Rivals. It is a fighting game with simple RPG elements such as stats and items with unique powers. We have a lot more planned for it in the future, but wanted to get the game out as soon as possible. The game also allows you to fight your friends through Facebook.
The game data including the user/character profile is all on my servers hosted on linode. We have 3 servers- [primary mongo], [secondary mongo], [mongo arbiter, redis(for leaderboards), nginx forward proxying to 4 tornado processes]. I chose to use mongodb because it seemed to fit our needs very well for a database. Our user/char data is always queried together, and therefore we don't need to do many joins. The data is sent and parsed on the phone as a json, therefore it is extremely convenient to keep the data in a collection instead of constructing it every time.
Link to the game: https://play.google.com/store/apps/details?id=com.pixelmaji.monsterrivals