This may not seem immediately obvious, but I've just finished reading
50 Years of Text Games, which goes in depth on 50 different, well...text games, throughout the years. Although it's not about virtual worlds directly, many of the games featured were attempting to create worlds completely through text in a way that was immersive and believable.
Fallen London, for instance, is one that managed to achieve this and saw a lot of success for it (and is featured in the book).
If you're interested in creating non-3D worlds, or in writing for any type of virtual world at all, it's a very good read.