Win an Emmy, get a lot of pre-debut press and have a gigantic first season that viewers can't stop watching, and what do you get? A record return for "Game of Thrones."

The adult fantasy series based on George R.R. Martin's book series premiered Sunday to 3.9 million viewers, according to Entertainment Weekly, boosting it by about 1 million people from its first season finale, and 74 percent from its series premiere.

That's excellent news for HBO, which already had solid plans to renew the show for a third season. With that large of a boost in viewership, the decision is even easier, which means Martin better get working on future novels since this is a show that appears to be sticking around for a while.

"Game of Thrones" has found huge success for HBO despite its highly complicated political storyline, and its environment that is virtually foreign to many viewers, including those who enjoy fantasy. The show not only survived the surprising death of one of its lead characters near the end of the first season, but has thrived ever since.

Peter Dinklage, who won an Emmy for his role as Tyrion Lannister in the series, earned star billing in the opening credits of the ensemble cast, sharing those honors with Lena Headey, who plays his sister, the Queen Regent Cersei Lannister.

The premiere topped two other recent high-profile cable premieres: "The Killing" on AMC, which picked up a lower 1.8 million viewers, and its fellow show "Mad Men," which captured 2.9 million viewers after a long break.

When HBO accounts for all three airings of the second season premiere, "Game of Thrones" was watched by 6.3 million people, according to EW.

Such a large audience ensures a renewal, but "Game of Thrones" was likely already getting one. Unlike network and basic cable channels, premium cable channels like HBO do not depend on actual viewers for its original programming to get a return on investment. That's because HBO does not show advertising during its broadcast, and isn't earning revenue based on the number of people watching those advertisements.

Instead, premium cable channels offer original series as a way to boost its subscription base, whether those new subscribers watch the new show or not. "Game of Thrones" has given HBO plenty of buzz in the media, and during awards season, and that buzz typically turns into more people willing to pay a higher cable bill to make sure they have HBO on their system.

It's why other premium cable channels like Starz renews some programs, like Kelsey Grammer's "Boss," before it airs a single episode. Success for these channels is counted by the number of new subscribers brought in (or the number of subscribers retained that may have departed otherwise), not by the actual number tuning in.

Despite the huge numbers, "Game of Thrones" still pales in comparison to audiences generated by shows like "The Sopranos," "Six Feet Under" and even "True Blood," those series many times bringing in nearly double the audience. However, during a time period when many television shows dip in the ratings (early spring), the ability to significantly grow an audience from season finale to next season premiere is extraordinary -- especially for one that takes the casting and story risks that "Game of Thrones" does.

"Game of Thrones" airs Sundays at 9 p.m. ET on HBO.