According to Buzinga, there are 4 main areas in any game that lend to an engaging experience. Exhibited below are the fool-proof rules they recommend you follow when developing a game users will love and share.
(image: http://www.buzinga.com)
They claim that the absolute most important aspect of an online or mobile game is that of the user experience. If kept in mind at all times, Buzinga believes that you are likely to succeed.