" If you’re not giving people the ‘I rock’ vibe, you’re not getting people to stick around.” The “I rock” vibe is another way of talking about classic game rewards, such as having a clear sense of purpose, making an obvious impact, making continuous progress, enjoying a good chance of success, and experiencing plenty of fiero moments. "

― Jane McGonigal , Reality is Broken: Why Games Make Us Better and How They Can Change the World