The network effect is one of those critically important, foundational concepts needed to discuss the success or failure of multiplayer games intelligently, one that gets more “what?” reactions than it should. I’m hoping people know it but perhaps not by that name; knowing it by name lets you tap a century of research and discussion rather than re-inventing the wheel.
The idea is that adding someone to a network creates value for everyone else. If you have no friends on Facebook, it is just a platform for solo Farmville. Every additional user creates additional potential value for every other user. In many of our online games and social network, the primary value we are seeking is that connection with other users. It is not just that users create content; users are the content.