Game design guru Raph Koster has an interesting post on how to define a game, to which he provides this definition and explanation:
Playing a game is the act of solving statistically varied challenge situations presented by an opponent who may or may not be algorithmic within a framework that is a defined systemic model.
Some see this as a “fundamentalist” approach to the definition. But I use it precisely because it is inclusive. It admits of me turning a toy into a game by imposing my own challenge on it (such as a ball being a toy, but trying to catch it after bouncing it against the wall becoming a game with simple rules that I myself define). It admits of sports. It admits of those who turn interpersonal relationships, or the stock market, or anything else, into “a game."
Emphasis mine. I think the definition is useful when thinking about Second Life, because it's broad enough to encompass what everyone who uses SL is apt to do -- some, most, or all of the time while in SL:
Of course, the many people who play mini-MMOs in SL like Bloodlines or casual games like Tringo are playing games. But then, clubbing socializers who make their goal to seduce that gorgeous avatar across the room are also playing a game. As is the sandbox builder whose goal is to create an X object. As is the in-world designer who wants to sell Y fashion items. Or for that matter, customize one's avatar to look like Z persona. (Which every SLer does, at least a little bit.) All of these represent self-defined, self-imposed mini-games within the larger, open framework.
This isn't to say everything in Second Life is a game -- for instance, Raph goes on to write about interactive, immersive art experiences which fit in the "digital interactive art" bubble (SL works by someone like Bryn Oh likely fit well there), which aren't games in themselves. Then there's socialization in itself, or the enjoyment of live music in itself. But approaching the question with Raph's definition in mind, I'd answer the question, "Is Second Life a game?" by saying, "Not exactly -- though everyone who uses Second Life plays games in it."Tweet