Gamasutra's feature today is super-interesting, and very accessible even for the "tech challenged" (like me). I'm often fascinated by motivations for play, especially when they're things that seem tied to instinctual human behavior, and I'm incessantly curious about the formula that makes some games, like the WoW drug, addictive or compulsive where other games aren't, necessarily.
The feature, "Compulsion Engineers," by Tynan Sylvester, looks at detailed examples of certain human urges, behaviors and actual compulsions that are evolutionarily hard-wired into us since the beginning of time, and discusses the way games can tap into and make use of these deep-seated human needs.
When we talk about the word "compulsion", especially in reference to chronic poster-child WoW, it usually has a somewhat negative connotation, if not an overtly condemnatory one. But Sylvester's examples demonstrate how answering certain human compulsions are actually key to maintaining good emotional states, as opposed to the usual presentation of constant dependency.
Some of the kinds of behaviors include play-fighting, storytelling, exploration and accumulating status, things that humans have been knee-jerk fixated on since we were much more stupid and hairy. It's a great article, and worth a read, so check it out!