However, it was Doctor Who that first captured the 33-year-old's imagination. "I was obsessed with it and I still love the old series," says Christopher, who edited the New Zealand Doctor Who Fanclub's Time-Space Visualiser fanzine from 2003 to 2009, winning a Sir Julius Vogel award for best fan publication in 2010.
With its mix of different genres, Christopher believes that Empire State has more in common with the Time Lord's more freewheeling adventures than pure space opera. "I never really thought of Doctor Who as being science fiction and I never thought of myself as a science fiction fan," he admits.
"I never read proper sci-fi when I was young; I only picked that up when I was older. Empire State is certainly a sci-fi novel but I tend to write sci-fi in the same way that Stephen King writes sci-fi. Stephen King is a horror writer but he mostly writes sci-fi with a horror edge."
An early adopter of social media, Christopher first engaged with his British publishers, Angry Robot, through Twitter, which he joined in 2009. "I'd been involved in internet forums so I was used to being online, especially because it's a great way to stay in touch with our friends and family in New Zealand," he says. "Twitter is a really good place for communities of writers, editors and publishers. Angry Robot started in 2009 and I discovered them through their editor, Lee Harris. We share an interest in film, comics and books, so we naturally just started talking."
After meeting Harris in person at various sci-fi conventions, Christopher pitched Empire State to him over lunch in Nottingham. "I thought Angry Robot would be a good place for it because they aren't afraid to stretch the boundaries of genre," says Christopher, who decided to write a hardboiled future crime story after reading Raymond Chandler's The Big Sleep on a flight to San Francisco.
"I remember thinking wouldn't it be fantastic if it had robots in it," he laughs. "That was the genesis of Empire State. Chandler is obviously a genius and I would never try to imitate him or copy the style of those classics; I just wanted the flavour of it. Most of Empire State takes place at night; it's quite wet and dark. That also ties in with the golden age of comic books. I really like period superheroes like the Rocketeer, so I wanted to put that into the book as well."
Christopher hadn't spent much time in the Big Apple when he first wrote about the Empire State's mean streets. "When I decided to write a sci-fi detective story, I knew it had to be set in America," he says. "It had to be a noir city and New York is such an amazing art deco city. It's also the birthplace of superhero comics. I went there last September for a proper look around and I couldn't believe that I managed to get it right but Empire State is set in a parallel universe so I can fudge things."
Like fellow Kiwi sci-fi and fantasy authors Philippa Ballantine and Geoffrey Wilson who have also recently found international success, Christopher has no plans to write about his homeland.
"Everything that I've done has either been set in America or not on Earth, which suits my editor, who is based in New York. It's easier to sell something that has got that kind of familiarity to it. Whenever I find something that has a big New Zealand influence or is set there, it feels really weird. I don't know why; guess it's that hyper-familiarity."
Empire State (Angry Robot/Nationwide Books $24.95) is out now.