Gamasutra has an interesting interview with Brian Reynolds, chief game designer at Zynga. Brian Reynolds is a veteran in game design and previously worked on such core strategy games as Civilization II and Rise of Nations.
The interview is long (5 pages) but interesting in that it details the culture shock for a veteran game designer entering into the social gaming space.
There is also an interesting Q & A about the differences between designing a traditional video game and a social (Facebook) game. According to Mr. Reynolds, the key factor in designing a traditional video game is that the game must be fun. If it is not fun, it will not sell (though marketing, branding, etc may have a role in that as well). With social games, he says, the key design factor is the social element, even more than fun.
Based on my game play experiences and discussions with social game companies, I agree that the social interaction is key. In fact, one could say a Facebook game is designed around being social. But to say that this trumps the “fun factor” is a dangerous slippery slope. The moment we design social games that are entirely data driven and that designed around being social and push the “fun factor” to the back-seat, is the day the social games become boring and that people stop playing games on Facebook.