"Game of Thrones" scribes David Benioff and D.B. Weiss have opened up about the difficult process making the original pilot for the series, calling it "one of the most painful experiences" of their lives.

Guesting on the Scriptnotes podcast (via TheWrap) -- hosted by screenwriters John August ("Big Fish") and Craig Mazin ("Identity Thief") -- Benioff recalled that it took four years to get the pilot make. Once the original version was completed, they showed it to fellow screenwriters Mazin, Ted Griffin and Scott Frank for feedback.

"Watching them watch that original pilot was one of the most painful experiences of my life," Benioff said. "I mean, it’s probably like appendicitis and that. And Craig [Mazin], as soon as it finished, Craig said --"

Mazin filled in, recalling his comment to them, "You guys have a massive problem." He told Weiss and Benioff at the time to "change everything" -- which they essentially did, to the extent that "literally, so much of it was reshot that a different director got credit."

“And I sat there, and this show unfolds, the first episode, and I am stunned. Stunned," Mazin said with regard to the newly shot pilot. "And I very specifically remember walking out in between and you were there, and I said to you, ‘That is the biggest rescue in Hollywood history,’ because it wasn’t just that you had saved something bad and turned it really good. You had saved a complete piece of shit, and turned it into something brilliant. That never happens. Here’s the crazy part. You guys, it’s honestly true, you guys are like a die that has all 20s on it, and then there was one 1, and you happen to roll the 1 when you made that pilot. That was it, it was a fluke. Everything since then … Everything since then has been outstanding.”

The pilot that eventually made it to air was reportedly 92% redone, and received praise from Mazin for "taking a complete piece of shit" and turning it into "something brilliant."

"Game of Thrones" Season 6 premieres April 24 on HBO.