Speaking at a Game Developers Conference (GDC) panel last week, Epic Games’ Head of Publishing – Ed Zobrist – revealed several surprising details regarding Fortnite’s Battle Royale mode and the studios decision to ultimately forgo the $40 paywall.

With these new details emerging from the panel, Zobrist revealed that work on the Battle Royale mode had only just started once they launched Fortnite’s PvE game mode, Save the World, on July 21. Doing the math, that is only two months in development, as Fortnite: Battle Royale launched on September 26.

Zobrist credits the success of the quick development cycle to the studio’s Unreal Tournament team as they were brought over to complete the bulk of the work as they had the necessary expertise to implement and develop what was originally intended to be a PvP version of their PvE game.

It was also revealed last week, that due to Fortnite’s overwhelming success, Epic Games has since reworked their entire studio to dedicate the majority of their 700 staff to the game. This is quite the statement, especially considering that Epic Games is also working on the Unreal Engine, along with their games Battlebreakers, UT, and Spyjinx.

Fortnite’s most recent spike in popularity hasn’t been its only success though, as analytics from SuperData Research has shown that Fortnite isn’t only the most popularity game in the Battle Royale genre, but it also raked in more than $126 million last month, compared to PUBG’s $103 million. It’s important to note though, that while PUBG does sell cosmetic items, it is their $30 price that tag that earns them the most revenue, whereas all Fortnite’s revenue comes from cosmetics alone.

Interestingly, Zobrist went on to state that Battle Royale was originally planned as an optional PvP game mode for Save the World when they realized their initial game wasn’t the big hit they had hoped for. With this in mind, players would have been regarded to fork out at least $40 just to play the Battle Royale component. However, the decision to separate the two different games came just two weeks before the game was set to launch.

Developing a game with such a small development window and making such drastic changes just weeks before its release is no easy feat, with Zobrist adding “I doubt any major publisher could have pulled off this kind of pivot in the time we ended up doing it.”

Fortnite: Battle Royale is showing no signs of slowing down anytime soon, with the game now reaching mainstream attention, it is now attracting the likes of many celebrities and popular sports stars. With Epic Games’ recent announcement of a 50 vs. 50 Celebrity Pro-Am this June, the game is only set to skyrocket even more.