Social games are that kind of games which use many options available on websites like Facebook. They are really great solution to get more users to your fanpage or for some contest with real prizes.
We can produce a game that will use Facebook API to fully integrate the game with Facebook users – they can publish their scores on the wall; inform theirs friends about new app to get some items or more lives inside game; use some data of the user (funny example: imagine a game where you can shoot to your friends photos with darts) and many more!