The concept of a Storytelling Engine comes from John Seavey's blog, 'Fraggmented', mainly about comics, but sometimes TV shows or films, he looks at the basic premise or status quo used to generate stories for serial adventures. For example Spider Man's classic engine (as reused and kept to in Ultimate Spider man) is "young nerdy guy without much money who's at school and working for a newspaper is also a superhero by night, keeping new york safe from a variety of, mainly animal and science themed super villains". He has posted storytelling engines for a while now, and they make interesting reading, particularly when he analyses why an engine works or doesn't work.
A major reason 'Heroes' started to go haywire after the first series is it's lack of a storytelling engine. It's much easier to make new stories if you have a clear, established status quo, and many modern comics which go on about changing the status quo forget this. If you're going to change the status quo in a comic, it should be rare and monumental. It should also STAY like that for a decent length of time, unless it's a sort of endgame climax. Harry Potter uproots it's storytelling engine only in the final book leading up to the big finale. Ultimately, if you have a good storytelling engine, you shouldn't need to change the status quo. It will generate thousands of stories. Doctor Who has a brilliant storytelling engine, as does 'The Simpsons'.
I guess my point is that I need to establish certain base rules about the setting and recurring cast. I often find when making comics that, having defined the characters, I can just dump an event on them and the story writes itself .
The cast need to be appealing enough that the player will want to keep coming back to see what happens to them 'this month' and there should be some consistent elements as a backdrop to the adventures. If, at the end of an episode, things go largely back to normal, we can make it so you can play them in any order, though actually there may be more interest in keeping some kind of continuity, encouraging players to play every episode and enjoy the gradual changes.