Book excerpt: In 1974, the release of Dungeons & Dragons forever changed the way that we experience imagined worlds. No longer limited to simply reading books or watching movies, gamers came together to collaboratively and interactively build and explore new realms. Based on four years of interviews and game recordings from locations spanning the United States, this book offers a journey that explores how role-playing games use a combination of free-form imagination and tightly constrained rules to experience those realms. By developing our understanding of the fantastic worlds of role-playing games, this book also offers insight into how humans come together and collaboratively imagine the world around us.