Vividly imaginative people experience life as a contest between mundane reality and extraordinary dreams, with mundane reality usually the victor. Not so Gary Gygax. Gygax, co-creator of the role-playing game Dungeons & Dragons, forged a successful business by sharing his fantasy universe with millions of fellow dreamers. In interviews following his death on March 4 at age 69, one word came up repeatedly: wizard.

Gygax was raised in Chicago on a diet of science fiction (Fritz Leiber, Jack Vance -- the good stuff) and chess. In the 1950s and '60s, he was an avid player of war games in which miniature plastic figures fought kitchen-table skirmishes. At first those battles, set chiefly in the Middle Ages, were realistic. Then Gygax introduced elves and wizards. A friend suggested that each player do battle as a single character rather than manipulate many. Those innovations -- fantasy adventures, role-playing, interactivity -- evolved into Dungeons & Dragons, the sire of today's immersive, avatar-driven video games.

While conjuring alternative worlds, Gygax supported his family by working for an insurance company -- a profession surprisingly close to fantasy gaming. "If you squint at a D&D character record sheet, you'll see it's an actuarial table," observes Flint Dille, a screenwriter who worked with Gygax in the 1980s. "Insurers take facts about a person's life and build stats on it to figure out when they're going to die and of what. Gary said, 'Let's do that for a dragon. We'll roll a die for the odds."

For a game of the imagination, D&D created copious opportunities to sell stuff, including manuals, miniatures, blank grids, and multisided dice. In 1973, Gygax and Don Kaye founded Tactical Studies Rules to publish the game and market the merchandise. D&D took off rapidly with a broad audience. In 1983, TSR was No. 51 on the Inc. 500, with $20.8 million in sales.

Mildred Marmur, former head of licensing at Random House, remembers the excitement in 1979 when she acquired the rights to distribute D&D in bookstores. "When I got it for the adult trade division, the woman in charge of juveniles said, 'I'm going to shoot myself," says Marmur. "I got there first because she tried to learn the game before she called Gary." Marmur had been introduced to D&D by her 12-year-old son, who also benefited from the deal. "When Gary was in town to meet with us, he'd stay at my house and run games there," she says. "Nate was the most popular kid on the block."

Gygax had his share of failed campaigns. After Kaye died in 1976, Gygax crossed swords repeatedly with his new partners. He gained control of the company, then lost it and lived for a period in semiexile from TSR. In 1997, game publisher Wizards of the Coast acquired TSR and brought Gygax back as a consultant. (The D&D brand now belongs to Hasbro.)

In 2001, Gygax signed with his final publisher, Troll Lord Games. Since then, five Gygaxian product lines have produced as much as 50 percent of the small company's sales. "We still have a lot of Gygax material, things he wanted to get out there," says general manager Stephen Chenault. "As long as the heirs are happy, the adventure continues."