Gamasutra: One of the GDC 2005 roundtables featured a discussion about instancing and its place in massively multiplayer gaming, with speakers both supporting and discounting the value of personalized game zones. What are your feelings on this trend in MMO game design?

Jessica Mulligan: I think instancing is a positive step. It isn't the end-all and be-all, however; it is one piece of the puzzle. There are times when players want to have a short, sharp experience with a small group of buddies without having to worry about the occasional griefer or other jerk ruining the experience; instancing is perfect for that.

There are also times when players want to engage in huge battles or intricate, static quests, or festivals, or live, human-run events. We need to make sure we have as many of those choices available as we reasonably can. Instancing is all about giving players more choices, and that is a good thing.