There are a number of multiplayer interactive Internet games, such as Xtrek. But more interestingly there have emerged in recent years a set of role playing environments known as MUDs (Multi User Dungeons) or MOOs (after Lambda Moo, one of the original ones).
Some of these (such as the Jupiter project at Xerox PARC) have been extended to include Virtual Reality (graphical subjective views of rooms and other simulated pieces of the real world).
An exciting development has been the use of the World Wide Web to provide access and structure to such environments, as for example, with Web World. At the time of writing this book, these had not reached full potential, but they may represent a large market in the future.