Standing on top of a temple in Egypt I had a vision of how to change the world with play. Games and work both require decisions, only games are often more engaging. Today we can use what people are naturally inclined to do to architect systems of engagement to better themselves and their world. We can use these games to succeed where corporations and public service institutions have failed. We can use the psychology of fun to create games of engagement to make us happier and smarter, help us achieve our goals, solve challenging problems like poverty and climate change.