Watch Gary Gygax speaking on a panel at GenCon 2007

As the creator of Dungeons & Dragons, Gary Gygax was an idol to millions of geeks around the world. But he was also the visionary inventor of a new type of interactive hobby, the role-playing game, one that sparked a rekindling of interest in the fantasy genre and was a key inspiration for the billion-dollar computer game industry. As such, Gygax’s influence spread beyond the legions of pallid school misfits who knew his name, and came to permeate popular culture as a whole.

Ernest Gary Gygax was born in Chicago in 1938, and moved to Lake Geneva, Wisconsin, aged 8, where he lived until his death. His father, a Swiss immigrant violinist in the Chicago Symphony Orchestra, introduced him to fantasy novels at a young age.

Gygax dropped out of high school, although he took anthropology classes at the University of Chicago, and worked as an insurance underwriter in the 1960s. He became an avid fan of traditional board-based war games, particularly medieval battles. The first step towards Dungeons & Dragons came when Gygax introduced fantasy elements from the pulp authors he devoured.

“The guys were getting a little tired of military miniatures, so one day I put a troll under the bridge, had a giant dragon and all that kind of good stuff,” he said in 1987. “Well, they loved it. They absolutely went crazy for it.”

This evolved into Chainmail, a fantasy war game still played with minature pieces. This was stripped down by Gygax’s fellow gamer, Dave Arneson, into a game where each player was represented by just one piece. The pair then codified this into an early version of Dungeons & Dragons.

The game did away with the board, relying only on graph paper, pencils, imagination and many-sided dice. Each player created an avatar from a class — warrior, wizard — and a race — dwarf, goblin, elf — and set off on a fantasy expedition guided by the Dungeon Master and his thick book of rules.

The goals included finding a hoard of treasure, or defeating an evil magus, and making sure to kill everything along the way. Games could last for several days, and there was no obvious way to win. It seemed an unlikely hit. “People said, ‘What kind of game is this?’ You don’t play against anybody. Nobody wins. It doesn’t end. This is craziness’, ” Gygax said in 1983.

Undeterred, in 1973 Gygax and Donald Kaye founded a company, Tactical Studies Rules, to develop the game. Dungeons & Dragons hit the shelves in early 1974. The game sold only 1,000 copies in its first year.

Gradually though, as teenagers across American met for furtive games in their parents’ basements, D&D became an underground hit. A tournament version, Advanced Dungeons & Dragons, was introduced in 1978, and the game became a phenomenon on college campuses. Gygax began receiving late-night phone calls from players asking for clarification of the rules. Sales of the game reached $8.5 million in 1980 and $29 million by 1985.

Many adults, however, were suspicious of the new craze. Religious groups accused the game of spawning satanic cults. Newspapers linked it to a variety of teen murders and suicides. Although he later joked “that really pushed the sales up”, at the time Gygax received death threats and for a while had to employ bodyguards. He always insisted that the claims were absurd, and that D&D was good for imaginative development.

Although the furore passed, and a D&D spin-off cartoon became popular, the game itself seemed to have peaked. Gygax lost control of TSR in the mid-80s after a legal tussle. The company was sold in 1997 to Wizards of the Coast, which later became part of Hasbro. There followed a D&D film, with Jeremy Irons, and a computer version of game, both to poor reviews.