Next Generation has a piece up discussing how game franchises evolve, what makes them succeed, and (in the end) what can make a game franchise fail. From the article: "We regard the evolution of video games largely as the realization of a singular idea: realism. By 'realism' we mean capturing the external world in which we live. Like many art forms - such as photography and cinema - video games have largely been driven by developers' desire and consumers' appetite for greater realism. It is possible to argue that the popularity of cinema derives from the medium's flexibility and power to induce a sense of realism in the spectator, as movies - much like our lives - use language through dialogue, manipulate cinematography and visual effects, and sounds to represent the world or capture our imagination."

Link To Original Article