FUNDAMENTALS OF GAME DESIGN, SECOND EDITION
Persistent Worlds
A good many online games are not really games at all by the definition you learned in Chapter 1, "Games and Video Games." Persistent worlds such as World of Warcraft, EverQuest, Anarchy Online, and so on constitute permanent environments in which players can play, retaining the state of their avatar from one session to another. Persistent worlds present a number of special problems and design requirements, which this section discusses at a general level. For a more in-depth discussion, read Designing Virtual Worlds by Richard Bartle (Bartle, 2003), and Developing Online Games: An Insider's Guide by Jessica Mulligan and Bridgette Patrovsky (Mulligan and Patrovsky, 2003).
Persistent worlds significantly predate today's popular graphical MMOGs. Since 1978, a small but dedicated community of developers has been building, playing, and studying text-based persistent worlds called MUDs (multiuser dungeons or domains, depending on who you talk to) that could be played by groups of people over the Internet. In these worlds, in which players interact by typing commands, a rich culture of online role-playing evolved.
This book won't go into MUD design in any detail here; there is no commercial market for MUDs, and you can already find a vast amount of literature about the subject on the Internet. Many of the design problems of today's MMOGs, particularly those relating to social interactions among players, were solved—or at least studied—long ago in the MUD community.