Avatar, Virtual Worlds, Communities, and TBI

I’ve been thinking lately about how the movie Avatar, had some pretty compelling stories about how one can become more, interacting through the use of avatars. In the movie, the world was presented as a real place, but in reality, as seen through the imagination, it could be thought of as a virtual world.
There are a couple of places online called MUDs (short for multi-user dungeons or whatever) where people largely interact through text maps of spaces. I has been some time since I’ve been heavily involved in MUDs, but that sort of escapism does exist, and I would suppose that there could be much more immersive situations possible.
It would be nice if a community could be built up, which would be supportive of individuals with TBI. There are some interactions through Facebook which have been interesting, but I’d think more could be done if there were a more robust online community.