The popularity of the Game of Thrones is odd to me.

It's mostly blood and boobs + great production values.

The first seasons have the fantasy elements not taking that much importance or screen time. It was more similar to the Sopranos in Middle Earth than anything else and I think that was part of the appeal of the show.

It was mainly a show about politics and to be honest, I still think that the entire show would be more interesting if there was no supernatural threat beyond the Wall. 

Another reason is that geekdom has became mainstream in the late 90s, early 2000s. Harry Potter and The Lord of the Rings came around that time and they were very popular and so were the first X-Men movies and the Sam Raimi Spider Man trilogy. You might be surprised about fantasy but look at the Superhero craze. That also became mainstream.

All those kids that grew up in 80s and 90s become adults but their hobbies  didn't really change. They still continue to play video games and they still continued to buy comic books

I think the boobies helped some to try it out. A combination of word of mouth and word of boob.

I think it’s the way the subject matter is treated.

Back in the day, fantasy genres were treated as B movies. So, it had cheesy dialogue and situations. It was essentially aimed at kids and teenagers.

Game of Thrones has stronger characters who actually act and talk like adults. It makes them more relatable to mainstream audiences.

Because I can just watch it and not have to smell the 400 lb. D&D player next to me.

First of all, it is well done which brings in viewers.

Secondly, everybody is talking about it. So that brings more viewers in. Because people want to see what everyone is talking about. And people want to join in on group activities.

Boobs are one thing, but there is nothing more awkward than watching Game of Thrones with your parents and Littlefinger goes on a soliloquy while two lesbian prostitutes lick each other's bums.