Raph has a very interesting essay on game mechanics and the sort of things that make MMO’s so highly addictive, by way of an Easter Egg game he did recently.
Now, there’s no reward in this game, there’s no winner or loser, and there’s no endgame. Yet even during testing, I had to tear myself away, and when put into Metaplace Central, average session length for the day went up 50%. But… in some sense, it’s a crummy game. Why this effect? Because the Easter Egg hunt is a confluence of a lot of highly manipulative tricks.
What are the tricks? And how do they operate in MMO’s? Well, read the whole thing to find out why folks will raid four days a week or more, and why I go around with the title Exalted in front of my name.