Guild Wars has persistence and shared areas, for instance, but as soon as you leave a town, you're in an instance unique to you and your party. There are elements of persistence in games like League of Legends. Heck, there was a time when people wondered if you could call World of Warcraft an MMO with its instanced dungeons and lack of housing.
As with a lot of subjective categories, there's really no right or wrong place to draw the line, but pretty much everyone seems to think that there's a line to draw. More often than not, it's not even a matter of quality so much as a set of consistent characteristics. So what about you? Where do you draw the line between an MMO and something else? How do you define a game as being an MMO instead of a similar sort of game?
Every morning, the Massively bloggers probe the minds of their readers with deep, thought-provoking questions about that most serious of topics: massively online gaming. We crave your opinions, so grab your caffeinated beverage of choice and chime in on today's Daily Grind!