Epic Games’ Ed Zobrist told crowds at GDC that Fortnite: Battle Royale took only two months to develop and was originally not going to be a free-to-play game.

Fortnite was released in July last year, but the Battle Royale mode was not available until September.

“We started working on this just about the time Save the World was coming out,” Epic’s Ed Zobrist explained at a GDC panel. “Two months in development, launched in September 26. So let’s do some math: Save the World, the PvE game, launched July 21. Battle Royale comes out September 26.”

To make sure that the development cycle was met whilst maintaining the PvE version, arena shooter experts were brought in to do a lot of the work. “It was the Unreal Tournament team that popped over to pick up the charge for us to basically put originally what we thought would be a PvP version inside our PvE game,” said Zorbist.

The Battle Royale mode was originally going to be a part of Save the World, but Save the World is in paid early access, meaning it would have been lumbered with the $40 price tag.

Being stuck behind a paywall would have significantly slowed the growth of the game to what it is now, a game that has recently beaten PUBG to the top spot for the most players. It wasn’t until the final two weeks of development that the team switched to a free-to-play mode that would be seperate from Save the World.

Fortnite has been in development since 2011, but what is unusual is the speedy development and popularity of the new game mode that is so different to the original game.

“I doubt any major publisher could have pulled off this kind of pivot in the time we ended up doing it,” said Zobrist.

The game smashed Twitch viewer records when Canadian rapper Drake and streamer Ninja played the game. Epic is trying to eliminate the toxicity in the game by getting rid of friendly fire, but the game was also subject to bad press recently when it was at the forefront of the games addiction controversy.