The “Game of Prequels” has begun.

HBO now has a total of five Game of Thrones prequels in development, but it is likely we will only see one emerge victorious in 2020.

Entertainment Weekly reports that co-executive producer Bryan Cogman, who has worked on the HBO mega-hit since Season One, will be developing a fifth story set sometime in Westerosi history.

After showrunners David Benioff and Dan Weiss, Cogman is the third-most prolific writer for the show so is well qualified to pen a prequel.

In May, Techly reported that four writers had been asked to pitch concepts for how to continue the show.

Those four pitches are coming from Mac Borenstein (Kong: Skull Island, 2014’s Godzilla), Jane Goldman (Kingsman: The Secret Service, X-Men: First Class), Brian Helgeland (Mystic River, L.A. Confidential) and Carly Wray (The Leftovers, Mad Men).

At the time, it was reported that both Wray and Goldman are working alongside George R.R. Martin, the writer of the series of books (‘A Song of Ice and Fire’), which Game of Thrones is based on.

According to Martin’s Live Journal, he will also be assisting Cogman in developing the fifth story idea.

Everyone involved is maintaining the utmost secrecy, so we know very little about the stories in development. What we do know is that the prequels probably won’t tackle Robert’s Rebellion or Martin’s Dunk and Egg tales.

In the Live Journal post, Martin said that Cogman’s story is “set during a very exciting period of Westerosi history,” which doesn’t give away much.

“Meanwhile, Jane Goldman, Brian Helgeland, Max Borenstein, and Carly Wray are all at work on the other four successor shows. I’ve been working with them as well (some more closely than others), and I’m excited by some of the ideas they’re coming up with,” Martin wrote. “HBO should have a wealth of material to choose from. And that’s not even counting the four weird-ass series concepts I’ve come up with on my own, just for the hell of it.”

For fans, the more important question is WHEN.

It now looks like we won’t be seeing the final season of Game of Thrones until 2019, which would push the first prequel back to at least 2020.

We do know that none of the current cast will be involved in the prequels, so filming could begin earlier. But it’s very hard to imagine two Game of Thrones shows running at the same time.

Martin writes that one show will air in 2019 or 2020, with others “maybe later.” He hopes they’ll all make it, and in that case, we’ll be seeing the Game of Thrones universe on our screens for a long, long time.