The fantasy tabletop role-playing game was conceived of by friends at the heart of Wisconsin’s gaming community, and has evolved to become a global phenomenon

There are 15 of us crammed into a cellar beneath a nondescript house in Lake Geneva, Wisconsin. To the uninformed observer, there’s nothing to see down here: just two low rooms, bare breeze-block walls, a ceiling lined with pipes. Yet we’re all looking about the place in hushed awe, like tourists staring up at the ceiling of the Sistine Chapel. The people I’m with are journalists, bloggers and historians, most of them specialising in table-top games, and we’re here because this is not an ordinary basement. It sits beneath 330 Center Street, the one-time home of Dungeons & Dragons co-creator Gary Gygax. And in February 1973 something happened here that would change the world of gaming, culture and entertainment for ever.

Across town, at the Grand Geneva Resort & Spa, Gary Con XVI is in full swing. The annual convention organised by Luke Gygax in honour of his father has been taking place every year since Gary died in 2008. It started with a few hundred devoted fans, but now several thousand come to play D&D and many other wargames, board games and role-playing games. They pack out the building’s many conference rooms and corridors, hunched in groups around large tables laden with character sheets, dice and snacks; they dress up as warriors and wizards and attend talks. Many have clearly been playing for decades.