Here are some of our entries on immersive 3D online worlds:
Social Virtual Worlds vs. Game Play Worlds
From the Terranova blog at http://terranova.blogs.com/terra_nova/2007/03/next_installmen_1.html
" the meaning of virtual world could be derived from its own descriptive terms as a "virtual rendition of the world". Like the "real world", a virtual world is therefore a place where you as an inhabitant are expected to make sense of where you are, what objects are there (maybe even rearranging some of them) and communicating with others (human avatars or non human robots) that might be inhabiting the space with you. So the primary function of a virtual world is discovery then the creation of meaning through the manipulation of the world and communication with others within the world. So entering a virtual world is in a way is like entering the family home as a new born baby, as a child in the first day in kindergarten, arriving at college as a freshman, or as the intern in the first day on the job. So lets adopt the term "social and creative virtual world" or more simply "social virtual world" and see where that takes us.
This might bring us to suggest complementary terminology "game play worlds" to describe multi-player games. As we all know, there is plenty of social interaction and "off game" communication in most online games, and there is often a great deal of creativity as players shape their own characters and their own home turfs. However, I would posit that the primary reason users are in "game play worlds" is the game. Given that all games impose structure on the players with rules, tools and goals, this gives a pre-built context to any game play world. In stark contrast, many social virtual worlds started as true blank slate!" (http://terranova.blogs.com/terra_nova/2007/03/next_installmen_1.html)
Online World Timeline at http://www.raphkoster.com/gaming/mudtimeline.shtml