The game may be fictional, but the numbers are certainly real: $800 million in sales in one day, 13 million copies sold in 24 hours, a billion dollars earned in three days. Rockstar Games' GTA V immediately celebrated the highest-earning video game launch in history after it dropped September 17, with everyone from Danny Brown to Tyler, The Creator reveling in the release.

But those aren't the only striking numbers that rolled out as the game spread across the world: 241 songs, 17 radio stations and the series' first-ever score created by a team of four producers working with Rockstar's three-man music department all went into the massive and detailed soundscape that makes up the game's nuanced aural experience. In addition to German electro pioneers Tangerine Dream and seasoned composer Woody Jackson, Rockstar Music Supervisor Ivan Pavlovich tapped The Alchemist and Oh No, the producers who together make up the duo Gangrene, to help map out the sounds of Los Santos' fictional L.A., marking the first time the game would include an original score in addition to its tried-and-true radio station-based musical formula.

"The first thing we all had to remember, the most important thing, was to make sure the experience of the radio stations remained the same as all the other GTAs," said Pavlovich in a phone interview with XXL. "And then the purpose of the score is really to support the narrative and action of the game without ever getting in its way. Our goals were set really high for this game—we wanted to go and create as much original content as we could for the various radio stations. So we started reaching out to all of our friends, especially fans of the game."

Two of those friends were Alchemist and Oh No, who had previously worked with Rockstar on Chinatown Wars in 2009. Rockstar reached out to them more than a year ago—Pavlovich and his team, comprised of Tony Mesones and Jaesun Celebre, had been working on the game for a year by that point—and asked them to contribute. But the two worked mostly in the dark, making beats based on vague descriptions before tweaking and tightening them according to mission details as the process moved on.

"We know how Grand Theft Auto plays out, we know what kind of music we would want to hear towards that game, so we kind of went off that," said Oh No in an interview with XXL. "They would give us descriptions of certain missions, and we would just make music towards where they were going with that."

"We were locked in for the whole year," added Alchemist. "The other projects we were doing, we were sneaking off and getting work done. And obviously not using any samples for the game was another challenge, too, jumping through that hula hoop... We didn't see anything until probably three-fourths of the way in."