Diablo 3 has no real reward loop – there is only a frustration loop, which can be temporarily alleviated by using the Auction House. As the game progresses in the hardest difficulty (Inferno), the frustration part of the loop gets longer and longer, as upgrades become more and more difficult to buy. “The Power of Habit” has something to say about this, too: When the juice didn’t arrive or was late or diluted, Julio would get angry and make unhappy noises, or become mopey. And within Julio’s brain, Schultz watched a new pattern emerge: craving. When Julio anticipated juice but didn’t receive it, a neurological pattern associated with desire and frustration erupted inside his skull. When Julio saw the cue, he started anticipating a juice-fueled joy. But if the juice didn’t arrive, that joy became a craving that, if unsatisfied, drove Julio to anger or depression. […] For those monkeys who hadn’t developed a strong habit, the distractions worked. They slid out of their chair - Ho John Lee