At a hotel in Juneau, Alaska, Shea chanced on a battered book from the lobby shelves, The Eyes of the Overworld by Jack Vance (1966).

Shea moved to the Bay Area where (prior to 1987) he held a variety of occupations, including instructor of languages, construction laborer, and night clerk in a Mission District flophouse.

[3] Nifft showed that Shea had developed the exotic style of Vance and Clark Ashton Smith, plus the ingenuity of Fritz Leiber's Gray Mouser stories, to produce an extravagant quest novel.

[1] Shea followed up with The Color out of Time (1984), a work influenced by the Cthulhu Mythos, and In Yana, the Touch of Undying (1985), about a vain opportunist's search for immortality in a land of fable.

Shea continued the adventures of Nifft in The Mines of Behemoth (Baen, 1997), serialised one year earlier in the Algis Budrys magazine Tomorrow Speculative Fiction, and in a novel The A'rak (2000).

The Nifft stories are "sword-and-sorcery" modeled on Jack Vance, notable for their imaginative depiction of the world of demons and their blend of horror, flowery diction, and occasionally crude humor.

[6] Reviewing The Incomplete Nifft, Elizabeth Hand declared that "not even Bosch could capture the sheer, obsessive teemingness of Shea's world.

[3] In 1994 Darkside Press published a limited edition of Nifft the Lean with a very long subtitle in "440 signed, numbered copies, bound in 'demon-skin'" (ISBN 0-940841-39-8).

[3][11][a] Shea has won major "year's best" awards, both conferred by the World Fantasy Convention and selected by open nominations and panel of judges.