This document discusses the future of serious games and the keys to making games fun and engaging. It introduces the 4 Keys to Fun framework: easy fun, hard fun, people fun, and serious fun. Examples are provided of games that illustrate each key. The document envisions a future in 2020 where games are used more widely to inspire change, foster discovery, and build empathy through play. Contact information and links are provided to learn more about the 4 Keys to Fun and related work.