Well, I just ran into ARGs recently, and I was very surprised to find no groups (at least no visible groups) about them on Myspace. So I took the liberty to make a group about them! Anyone familiar with the growing genre of gaming is encouraged to join!

Wikipedia definition of Alternate Reality Games:
An alternate reality game (ARG) is a cross media game that deliberately blurs the line between in-game experiences and the real world. While these games may primarily be centered around online resources, events which happen as part of the game may be communicated to the players in a number of forms. Previous ARGs have included the following:

-e-mail
-websites, both those obviously connected with the game and those innocent looking (see ilovebees) - often where the bulk of the game lies, these sites provide puzzles in many forms, e.g. cryptography
-phone calls to a player's home, cell or work phone
-phone calls from players to a fictional character
-SMS messages to players' cell phones
-postal (snail) mail
-newspaper articles or classifieds
-chat/Instant messaging, often involving conversation with actors or bots
-IRC channels
-real world artifacts related to the game in play
-real world events using actors who interact with the players who attend

Most ARGs have a specific goal of not only involving the player with the story and/or fictional characters but of connecting them to each other. Many game puzzles can be solved only by the collective and collaborative efforts of multiple players, and strong communities flourish around individual games and the ARG genre as a whole.

Alternate reality games are usually earmarked by a large game-reality in the form of multiple websites, all of which are presented as being real (non-fiction). In fact, sometimes it is difficult to tell if a website is fictional or not. These websites form the foundation of the game's universe, and are usually the primary storytelling vehicle, although the various media listed above can be used as well. This creates a situation where the game's alternate reality and the real world collide -- some games have extended into players' everyday lives by pushing information towards players at certain times (e.g. SMS messages), whereas others have required players to initiate all communication.

The concept of "this is not a game" is central to the ARG genre. Alternate reality games do not advertise themselves as such, and never admit to being a game while 'live' -- when the game is over, some information about its creation may become public. The mystery surrounding the game's events and creators is a major contributor to player immersion and enjoyment, as is the general thrill of discovering the game's alternate universe and exploring its boundaries with the real world.

Several ARGs have been used as marketing tools to promote certain products, from video games to cars. Although the web-based nature of alternate reality games means that financing them is easier than producing a full-scale video game, a long-running game has several ongoing expenses including (but not limited to): web hosting and bandwidth; web and graphic design staff; scriptwriting staff; actors; puzzle creators; real world artifact creation; telephone calls; advertisements in newspapers. Using an ARG as a marketing campaign allows players to form a deep attachment with particular products (e.g. being immersed in the universe surrounding a video game) while providing the resources necessary to run a full-scale game. Other games have financed themselves, for example through the sale of real-world artifacts.