MOO

Object Oriented MUD (Multi User Dungeon)

text-based Virtual World

One of the most distinguishing features of a MOO is that its users can perform object-oriented programming within the server, ultimately expanding and changing how the server behaves to everyone.[4] Examples of such changes include authoring new rooms and objects, creating new generic objects for others to use, and changing the way the MOO interface operates. The programming language used for extension is the MOO programming language, and many MOOs feature convenient libraries of verbs that can be used by programmers in their coding known as Utilities http://en.wikipedia.org/wiki/MOO

http://en.wikipedia.org/wiki/MUD

Mitchel Resnick (and Amy Bruckman) 1995 paper on MediaMoo as Virtual Community supported by Constructionism.