From a fantasy land where everyone has a stroke of evil and incest is considered "love", spawns a successive series of swords and sorcery in the TV hit, Game of Thrones.

"It is a lot of blood and guts and sex and stuff," star Emilia Clarke says of the screen adaptation of George R R Martin's bestselling book series, A Song Of Ice And Fire.

The dainty British actress, 24, has just finished filming series two of the R-rated Game of Thrones and said fans should prepare for a second course that is "even better" than the first.

The story follows a struggle for power across the seven kingdoms of the mythical and medieval country, Westeros.

As her white-haired character Daenerys Targaryen - a guise which requires more than two hours in make-up - Clarke has embraced a role requiring nudity and presenting confronting themes.

"I would let his whole tribe f--- you, all 40,000 men and their horses too if that's what it took," a timid Daenerys is told by her brother of his obsession with becoming king.

Indeed, the entire production is filled with social taboos, acts of savagery, revenge and betrayal.

Incest may be an act shunned in real life but in the context of Game of Thrones it is love, says star Nikolaj Coster-Waldau.

The suave Danish actor, 41, whose on-screen lust is for his fictional twin sister, is nonchalant about how viewers perceive his character's graphic sexual activities.

"Usually when you say incest ... you think of someone taking advantage of someone, something despicable, something horrible. Here, it is two consenting adults, it is love," Coster-Waldau said, shrugging his shoulders and sweeping a hand through his long hair.

Among the Game of Thrones cast members speaking with reporters in London ahead of the series one DVD release was Kit Harington, who said it is the "bad bits" that makes the production so appealing.

"I think people can relate to (the series) because it's about people's faults. It's about what people do for power," said British actor Harington, 25.

"It really is a fantasy that's based with a real sense of reality and the characters are faulted, every single one of them, in some way."

Within the first 15 minutes of episode one, a snow-covered hollow filled with severed body parts and decapitated heads on stakes is presented, followed by the beheading of an innocent man, complete with subsequent squirting blood.

"I think the appeal of this is that there is no (inherently good person) who's wonderful and does everything right," Harington said.

Production network HBO have spared no expense on Game of Thrones, with filming in Ireland, Iceland, Croatia and Malta.

The first series has already been screened in Australia on the pay TV channel showcase, with dates yet to be confirmed for series two.

Writers and executive producers David Benioff and Dan Weiss said they are not surprised by the global interest in Game of Thrones.

"We did think it would appeal internationally more than any show because it is not set anywhere in particular, so it doesn't exclude anyone," Benioff said.

Both men spoke of a third series but refused to give away details of the upcoming production.

Harington was less guarded but would speak only in general terms about series two, including that viewers can expect to see more fantasy, including dragons.

"It doesn't get any easier to watch, but there are certain elements of humour which come in which act as a balance," he said.

Episode one of the second season will air on HBO in the US on April 1 and on Sky TV channel SoHo in New Zealand with a double episode premiere on April 16.

Game of Thrones: The Complete First Season will be released on DVD and Blu-Ray on March 14.

- AAP