The importance of a games rules transcend the game itself. Listen to a group of 8 year olds playing a game, any game. A huge amount of time and energy goes into arguing about the rules of the game itself, sometimes taking up more time than the playing of the game itself. What children are arguing about when they argue about games is fairness. They are attempting to deal with the larger issues of who gets what advantages, and what degrees of freedom and constraint will be placed on all parties, a problem not unlike life.
Games allow a simplified feedback loop.
Thus great complexity and subtlety can be built up a change at a time. Had the developers of the original MUD set out to create a purely social arena like LambdaMOO, they would have failed. By starting with a game and letting it develop from there, places like LambdaMOO have been able to organize organically. These ideas of identity are only half of the perception of the net as a real environment, though. Two people talking on the phone also have identities, and people exchanging paper mail are as aware of how writing conveys a sense of identity as people exchanging e-mail.