E. Gary Gygax and Dave Arneson created the original Dungeons & Dragons fantasy role playing game in Gygax's basement in 1974. Several variations of the game have been created in the last 40 years.
Gygax became involved with playing wargames in the mid-1960's. He created a wargames convention in his hometown in 1968, named the Geneva Convention, or Gen Con for short. Role playing game enthusiasts gathered annually for the convention. Over time, the convention grew in popularity and moved to larger venues in the area. It was held in nearby Milwaukee from 1985 until 2003, when it moved to its current home of Indianapolis.
It was at one of the early conventions that Gygax met Arneson. They spent a few years developing what would become the most popular game of its type.