Though U.S. writers play a major role in speculative fiction's world scene, the United States is not its only source. We're not even the only English-speaking country to make contributions to the field: Canadian, British, and Australian authors have also produced thought-provoking science fiction and fantasy tales.

Margaret Atwood's "In Other Worlds: SF and the Human Imagination" (Nan A. Talese/Doubleday, 255 pp., $24.95) collects essays and excerpts by this renowned Canadian writer of both mainstream and speculative fiction ("The Handmaid's Tale," "Oryx and Crake," and her most recent novel, "The Year of the Flood," are arguably SF). Three previously unpublished lectures delve into her childhood enchantment with comics and pulp SF, her early attempts to create these kinds of stories, and her college study of myth, utopias, and other genre relatives.

The knowledge behind her insightful remarks helps explain how even her mundane work such as "The Robber Bride" invokes a sense of wonder. Atwood also addresses the controversy surrounding her rejection of the SF label; she says it's a misunderstanding stemming from her very narrow definition of the term, a definition involving gizmos and skintight unitards.

Atwood's reviews of George Orwell's "1984," Marge Piercy's "Woman on the Edge of Time," and other SF classics make up the bulk of "In Other Worlds," and it's a well-balanced and satisfying collection. But the book's crowning glories are the short fictions: humorous dialogues extrapolating current cryogenic practices, epistles from invading extraterrestrial moths, excerpts from nonexistent novels about planets full of virgins. They're tiny, tantalizing glimpses of the even larger library of science fiction this prolific (more than 40 books) author might have produced.

The output of Ken MacLeod, a native Scot, is a bit smaller than Atwood's, but it's still significant: he has published 12 novels and more than 20 short stories. With "The Restoration Game" (Pyr, 258 pp., $16), he joins the ranks of those blending science fiction adventure and stories about computer gaming. At the same time he addresses the "simulation hypothesis" with dash, aplomb and superb intelligence.

Familiar to most people from films like "Inception" and "The Matrix," the simulation hypothesis proposes that everyday reality is a hoax perpetrated by machine minds or aliens. MacLeod folds the related discoveries of his game-writing heroine Lucy Stone into a Len-Deightonesque expedition to an ex-Soviet satellite country, combining creepy Stalinist revivalism, callous war games, and explanations for some actual discrepancies in physics that make sinister sense in the context of the hypothesis. Kudos to Pyr for printing a U.S. edition of this witty and scarily logical book.

Richard K. Morgan is a Scot, too, though born in England. You could classify most of his previous novels as neo-cyberpunk, dealing as they do with switching bodies, and steeped as they are in film noir-like violence. But his new book, "The Cold Commands" (Ballantine/Del Rey, 493 pp., $26), is fantasy, as was "The Steel Remains," for which it's a sequel.

Importing an SF/cyberpunk sensibility into the sword-and-sorcery subgenre makes for interesting juxtapositions: quantum demons; black elves forging steel weapons and launching orbital AIs (artificial intelligences). If you haven't already read "Remains," let it introduce you to this bloody, exciting, dangerous world. "Commands" will carry you deeper into the ongoing saga of Ringil Eskiath and his companions, as they refuse the corrupt trappings of nobility. Yet they can't avoid being drawn into a quest to find an ancient enemy of the throne. The quest's scrambling lack of completion fits this novel's dark atmosphere like a fist inside a gauntlet of rusting chain mail.