HBO is buckling on its sword belt and smartly stepping into the realm of gritty fantasy as filming continues for their epic pilot of author George R.R. Martin’s “Game of Thrones.”

Based on Martin’s bestselling ‘A Song of Ice and Fire’novels, the series would follow the treacherous clash between royal families to secure ultimate power of the vast lands of Westeros. Royalty and knights play a perilous game of intrigue, where those gifted with unflinching resolve and a keen eye for subterfuge often conquer more than the greatest armies. 

Principal photography began in late October in Northern Ireland and is now wrapping up in Morocco. Tom McCarthy, who earned accolades for his work on 2003’s “The Station Agent” and 2007’s “The Visitor,” is directing. He’s working from a script penned by the pilot’s executive producers David Benioff (“Troy,” “The Kite Runner”) and D.B. Weiss.

‘Game of Thrones’ will span a novel’s worth of material per season if the pilot is picked up. But will the pilot get a hearty thumbs up from HBO when McCarthy turns it in? We’ll likely know early next year. But based on Martin’s remarkable books and on the respectful approach applied to assembling the cast and crew, I’d say there is a good bet here that HBO will have another “Trueblood”-caliber success, if not more.

After all, HBO is a ripe match for these novels — an expansive, adult, uncompromising tale, layered with characters and details so intricate that only a cable series could hope to carry its weight. Running time constraints and censorship issues are thankfully kept to a minimum, which is a significant merit HBO offers. Butchering these novels into a friendly mainstream film or a network TV format would be a crippling blow to what makes the source material so special.

And it seems Martin, who also serves as an executive producer on the pilot, is glowing about his novel’s treatment by HBO. Having served as a writer on “The Twilight Zone” (1986) and a writer-producer on “Beauty and the Beast,” he is no stranger to television productions, and was recently on set in Northern Ireland meeting the cast and viewing the filming.

“In between signing and mooting, I’ve been hanging round the shoot, trying not to get underfoot,” Martin said in a LiveJournal post. “‘How is it going?’ everyone wants to know. I think it’s going great. Wednesday’s location was amazing, so real I could hardly tell where the real castle ended and our fake castle began. 

“I saw Bran and Tommen swatting at each other in the yard, Joffrey taunting Robb, the Hound growling at Ser Rodrik, while Arya displayed her wretched needlework to Jon above, and it all looked wonderful. Saw some of the footage from the crypts too, and that looked amazing as well. Yes, some things are not exactly as they were in the books, that’s inevitable with any adaptation … but these are my characters and this is my story, and it’s thrilling to see ’em come to life.”

The novel “A Game of Thrones” quickly won readers over when it hit the shelves in 1996, later winning the 1997 Locus Award, and receiving nominations for both the 1997 World Fantasy Award and the 1998 Nebula Award. More awards followed for subsequent books in the series. Seven novels are planned, with the fourth volume, “A Feast For Crows,” being the latest.

In short, HBO has chosen to enter the fantasy genre on the best possible footing by selecting Martin’s books. And it may earn them untold bragging rights.

These are historically rich novels, taking frequent cues from European history and the complex relationships facing royalty to maintain control of their thrones. Castles and grand tournaments featuring renowned knights are often the backdrop of elaborate intrigues. As the details mount, Westeros becomes a believable and wildly fascinating realm. Martin initially takes his time to set his story in motion, but once his many pieces are in place, the story soars, carrying an abundance of surprises and tension. It doesn’t shy away from sex or the hard realities of violence either. The consequences resulting from those who abuse power are starkly drawn. In many ways, the show’s potential nasty vibe could be classified as “Deadwood” meets a fantasy setting.

Magic, the undead “Others” and dragons do appear, but rarely; instead, human drama dominates. A typical character of Westeros is often a mix of good, bad and somewhere in between. No simple bad guys lurk here. You may despise one character early on, only to find yourself championing their actions in later pages. And like writer-director Joss Whedon (“Buffy the Vampire Slayer”), Martin is not averse to killing main characters, often with sudden, heartbreaking and disturbing effect.

Casting the series was obviously a pivotal step, and actor Sean Bean (“The Lord of the Rings: The Fellowship of the Ring”) was brought aboard to provide a solid anchor for the pilot. He plays lord Eddard “Ned” Stark, a man of unwavering honor who is obligated to leave his lands to help his friend and king, Robert Baratheon (Mark Addy), to govern Westeros.

“For the movie fans out there, Sean Bean needs no introduction,” Martin said. “I mean, what the hell, he was Boromir and he was Sharpe [in the series of TV movies], he was terrific in both roles, and in a hundred other parts besides. I can’t imagine a better Ned.”

Joining Bean for another critical role is Lena Headey, who stars as twisted queen Cersei Lannister. Heady played the title character in the Fox series “Terminator: The Sarah Connor Chronicles,” and played Queen Gorgo in the Frank Miller feature film “300.” 

And often cited as a fan favorite of Martin’s novels, Tyrion Lannister — the cunning dwarf brother of Cersei — is played by Peter Dinklage, who worked with McCarthy in “The Station Agent.” That film landed Dinklage an Independent Spirit Awards’ Best Male Lead nomination.

Other key casting announcements have included Nikolaj Coster-Waldau (“New Amsterdam”) as Cersei’s twin, Jaime; Jennifer Ehle as Eddard’s wife Catelyn Stark; Tamzin Merchant as the dragon queen Daenerys Targaryen; Kit Harington as Jon Snow, Eddard’s bastard son; and Jason Momoa (“Stargate: Atlantis”) as Khal Drogo. 

All in all, “Game of Thrones” ranks as one of 2010’s top projects to follow. It’s truly an exciting time for fantasy fans — novels of the highest caliber may be heading to the small screen on a weekly basis, shepherded by a network with an impressive record for quality programming. Like the knights of Westeros, HBO should ride high.