Now that the social layer has been built, some people say the next layer will be the game layer. The game layer will install game mechanics in everything, and game mechanics are a way to manipulate human behavior. The optimists say that we can use game mechanics to manipulate ourselves to be better—nicer, more productive, not as fat—and that the companies who figure out how to install that layer will be the next Facebooks. Here’s how Rahul explains it: ‘The biggest trend in Web applications right now is adding game design. With the theory of game design, you want a curve like this: increasingly large payoffs at random but increasingly spaced intervals. So the first payoff is very small, and the next payoff is a little bigger, and the next one… To begin with, you get a payoff one out of five actions, then it’s one out of twenty, then it’s one out of fifty—but those intervals have to be random. That is the key to human addiction. And any system that has that property, whether it’s Facebook, World of Warcraft, or physical drugs—that’s what makes business work. Facebook is very watered-down. They could ratchet up the gaming significantly.’