2012 has been a year of transition for science fiction and fantasy literature. SF's reputation as home of the Bearded White Male hides a more interesting story. SF is the literature of geeks, and today, geeks run the world. Geek culture isn't infiltrating the mainstream: it is the mainstream. And geeks come in all ages, genders and backgrounds. This year, the Hugo and Nebula award shortlists demonstrated SF's growing diversity, even as the decision of the editorial team at Weird Tales magazine to publish racist screed Save the Pearls demonstrated many of its ongoing challenges.

Even in the age of the ebook, word-of-mouth is still what makes a breakout hit, and many of the books to watch in 2013 have been building excitement through 2012. Madeline Ashby's vN: The First Machine Dynasty is the outstanding hard-SF novel of the year and deserves to feature in many award ballots in 2013. Some Kind of Fairy Tale by Graham Joyce has brought the veteran English novelist and World Fantasy award winner to the attention of a growing audience, as have film adaptations in the pipeline for this and his previous novel, The Silent Land. And G Willow Wilson's Alif the Unseen stands out as among the most original and challenging books of 2012, and my personal pick for at least one major award in 2013.

M John Harrison's masterpiece recognised

With the novel Empty Space in 2012, M John Harrison concluded his Kefahuchi Tract trilogy begun with Light in 2002 and Nova Swing in 2006. Empty Space and its precursors paint their drama across a canvas reaching from the infinite scale of space-time, down through the quantum universe and into the depths of the human heart. Harrison's masterpiece is the outcome of a decades-long project to fuse the conceptual strength of SF with the human insights of literary fiction. Robert Macfarlane, chair of the Booker prize judging panel in 2013, picked Empty Space as his book of the year recently, and it's unlikely to be the first plaudit as more literary readers discover M John Harrison's remarkable writing.

SF writers move to the mainstream

Writers of literary fiction from Michael Chabon to Colson Whitehead have demonstrated their love for SF in recent years, and in 2013 the popularity of the genre will find many of its best writers garner mainstream attention. Lauren Beukes's The Shining Girls is tipped as one of the hot books of the year after being purchased by HarperCollins for a high six-figure advance. Beukes's highly acclaimed Moxyland and Zoo City from publisher Angry Robot were some of the most highly acclaimed SF novels of recent years. Fantasist and icon of weird fiction Jeff VanderMeer recently announced a major three-book deal with Farrar, Straus & Giroux for his Southern Reach trilogy to begin publication in 2014. Moreover, the famed literary imprint are responsible for one of the most notable genre-crossover hits of this year, Mr Penumbras 24 Hour Bookstore by social media star Robin Sloan.

Space is SF's new black

Once upon a time our imagination populated outer space with exotic alien civilisations, and the space race inspired thousands of SF novels through the 60s and 70s. But when exploration revealed nothing but a barren solar system and infinite vacuum, space fell somewhat out of fashion, even within SF. Now, though, the discovery of Earth-like exoplanets, the Curiosity rover touchdown and the media sensation of Felix Baumgartner's space jump are exciting people about space again. Surfing the zeitgeist of space is James Smythe's The Explorer, a thriller of deep-space exploration with overtones of the best 70s space-based SF. Ian Sales' Adrift on the Sea of Rains is one of the most outstanding self-published books of the year, and a homage to the golden age of SF writing and the Apollo space programme.

All hail the Kindle serial

Serial fiction has been threatening a resurgence for as long as people have been publishing on the internet. But 2013 may be the year it happens – and John Scalzi may be the writer to kick off the revolution. Along with publisher Tor books, Scalzi is planning to serialise the next novel in his hugely popular Old Man's War series via the Amazon Kindle platform. The Human Division begins serialisation this month with new instalments each week, but has already entered the Kindle bestsellers list. The Kindle seems like a natural platform for serial fiction, so expect to see hundreds of other authors and publishers following suit if Scalzi's experiment is a success.

American Gods become legend

It's hard to imagine Neil Gaiman becoming any more famous, but we may have to put our imagining hats on as his cult novel American Gods makes its way to our television screens. HBO discovered an audience for epic fantasy with George RR Martin's A Game of Thrones and are hoping to find equal success with Gaiman's urban-fantasy reimagining of contemporary America. Rumours abound that the network have already committed to six seasons of the drama. 2013 also sees the publication of Gaiman's latest novel, The Ocean at the End of the Lane. Short of a late Mayan apocalypse, it's hard to see any scenario in which 2013 will not be Neil Gaiman's year.