Dungeons and Dragons artwork by Erol Otus

If you mention Dungeons & Dragons to most adults, you will find that the name inspires either a big grin of nostalgia -- or a blank stare.

What seems like a nerdy pastime full of math and maps and dice is also a key to a unique fantasy experience unlike books, films, or video games.

Many of Dungeons & Dragons current crop of players were not yet born in 1974, when the idea of "role-playing games" first emerged among the niche hobby of historical war gaming.

Author and life-long gamer Jon Peterson documents the surprising story behind Dungeons & Dragon's creation and early success in his book Playing at the World: A History of Simulating Wars, People, and Fantastic Adventures from Chess to Role Playing Games.