Game you can choose the best in different categories and subcategories like Sports, Filmstars, Movies etc.., challenge your friends to play game and see result board who is winning. Interactive UI is the base requirement when it comes to social networking applications.
First glance requirement seems easy achievable but it is not always the case specially when requirement gradually grow. Normalize database structure and proper architecture for the coding helped us to grow it easily over period.
Application started with basic gaming that is limited to one user that gradually increased to facebook integration, Invite friends to install app, Challenge your friends to play game under particular category, compare score, see result dashboard and push notification to update about where your friend stands in compare to your friends.