I wrote a brief article for the IGDA Newsletter (link below) about writing stories for casual games. The point of the article was to toss out some ideas about ways to approach casual game writing, rather than try to write a "how to" guide.

Basically, I recommend (against my better instincts) using traditional story structures and stereotypical characters in order to simplify the player's task of digesting the plot. The analogy that I used in the article, and that I really like, is the "gutter" in comic strips. That white space between two panels has nothing in it, but the human imagination fills in everything that could have been written there. In much the same way, all you need to do to create a story is to suggest where you are in the story arc and what the characters are thinking; there is no need to be more explicit than that. The player's imagination is more than capable of connecting the links and filling in the details.

Hope you like it.

 "Short Games, Long Stories"