CLEVER AND SWEET and a bit sad, the cover of Empire of Imagination: Gary Gygax and the Birth of Dungeons & Dragons riffs on the cover of 1985's Advanced Dungeons & Dragons: Unearthed Arcana. But while Unearthed Arcana's cover boasted an ancient wizard perusing a weighty tome—surrounded by vials of strange elixirs, a demon's skull, and a sputtering cauldron—Empire of Imagination's features a middle-aged guy smoking a cigarette. The book is now a typewriter; the smoking vials a carton of buttermilk and an empty beer can. Where the wizard's study looked out onto a two-mooned sky, this window reveals Lake Geneva, Wisconsin, where Gary Gygax—the guy at the typewriter—became one of the creators of Dungeons & Dragons.

Gygax's life was as memorable as any dungeon crawl: Not only did he revolutionize gaming, he also helped pave the way for mainstream fantasy like Game of Thrones and influenced a generation of authors, programmers, game designers, and Vin Diesels. D&D's 40-year history features cameos from everyone from Stephen Colbert to Tipper Gore; a game once relegated to moldy basements is now part of a multibillion multinational corporation.

The story is interesting enough that one wonders why biographer Michael Witwer felt the need to dramatize it: Unlike earlier, better books about Gygax and his legacy—David M. Ewalt's Of Dice and Men and Ethan Gilsdorf's Fantasy Freaks and Gaming Geeks spring to mind—lengthy sections of Empire of Imagination are written as if they were a novel, with Witwer attempting to get into Gygax's head as he makes the leap from Wisconsin gaming nut to Hollywood mogul taking meetings with Orson Welles. (Welles, it turns out, briefly considered playing a "villainous mage" in a Dungeons & Dragons movie.) Gygax's story is one of betrayed friendships, corporate machinations, government surveillance, media controversy, and a mansion called "Dragonlands"—in other words, fascinating stuff, regardless of how many 20-sided dice you own.

But Empire of Imagination hits a speed bump whenever Witwer tries to describe Gygax's mindset, be it at Gygax's wedding ("He quivered a bit as he stared into the eyes of his bride-to-be. He could hardly believe it, but she was his—the prettiest girl in town") or on his deathbed, where "a dark-robed figure" points to a chessboard ("'Wanna play?' said a raspy voice that chilled Gary to the bone"). In the meantime, big stuff is glazed over: Gygax's right-wing politics, his strained membership in the Jehovah's Witnesses, and his late-in-life coming to Jesus—not to mention drugs and booze and affairs—are dealt with as if mere footnotes. Thanks to interviews with Gygax's friends and family, Witwer characterizes the man as "a bit of a paradox: a pragmatic businessman meets freethinking hippie"—but, in favor of fictionalized asides, skims off much of the stuff that, in any biography, would be most telling. It's too bad, because the intertwined histories of Gygax and D&D are engaging enough. The last thing they need is more fantasy.