Rock, Paper, Shotgun has published a developers diary from senior game designer Bruce Harlick, one of the minds behind NCSoft's City of Heroes; it's an interesting look at the development process for the forthcoming Issue 13 update. It's a bottom-up glimpse into what's gone into designing the new Cimerora and Midnight Squad story arcs, and as Harlick explains, even updates aren't an easy design process:
One of the things our players are most interested in is how we go about the process of designing the missions and story arcs they play through so much. It's not just an easy process of throwing together some pre-created maps, plopping down some enemies to get rid of, and setting up the appropriate rewards. We carefully consider the plot of the missions or story arcs and their flow in the gameplay sense, what resources we can (or can't) use to achieve our goals, carefully balance difficulty with rewards, and consider how to creatively get the best out of what we are typically able to use to make the entire encounter much more interesting.
Worth a read, especially if you're a CoH devotee. Even if you're not, it's an interesting, real-life glimpse into the design process.
Behind The Scenes On City of Heroes [Rock, Paper, Shotgun]