Epic Games has gathered momentum in the past year as it made its Unreal Engine for game development available for free, said Tim Sweeney, chief executive of Epic, at a session at the Game Developers Conference today.

Epic is an important company in the game ecosystem, not just as a leading game developer but as a provider of the Unreal game engine. A year ago, Epic made its Unreal Engine available for free, with royalties on the back end for commercial games. Since that time, the company has gained 1.5 million users, Sweeney said. Seven Unreal franchises have generated more than $1 billion in revenues each, to date.

The company wouldn’t confirm how the total Unreal Engine users after GamesBeat asked in an email.

Epic has developed its own virtual reality demos such as Bullet Train, a bullet-time shooter game in VR. It is also working on Paragon, a high-end 3D multiplayer online battle arena game. It is launching with Steam Early Access starting on March 18. As a shooter game, “you’re right there in the fight” in Paragon, Sweeney said.

Sweeney said that Unreal Engine is supporting Vulkan, the graphics applications programming interface that is replacing the aging OpenGL API. Unreal is free to use, but Epic gets a 5 percent royalty on games that ship. In that respect, Epic succeeds only if a game succeeds, Sweeney said.

Sweeney also said that hardcore gaming is taking off on mobile in places like South Korea.

Using Unreal Editor in VR.

Above: Using Unreal Editor in VR.

Image Credit: Dean Takahashi

“Core gamers are spending a lot more time on mobile devices,” he said.

Blade is one of the examples of high-end Unreal games on mobile in Korea. “We are seeing the seeds of Triple-A mobile spreading all over the world,” Sweeney said.

Epic has already given out $700,000 in developer grants to Unreal Engine users. And it is going to award another $500,000 in the coming months.

Sweeney also shared a vision of Unreal Editor in VR on Oculus Touch. Mike Fricker and Nick Donaldson of Epic Games created the Bullet Train demo. And now they’re using tools to design games from within a VR world.

“This is just the beginning,” said Fricker. “We are making it available now to try on Github.”

Brendan Iribe, CEO of Oculus VR, joined Sweeney on stage to say that his company is using Unreal to make high-end VR experiences. As for using VR to create games, Iribe said, “This is something that I never thought possible.”

The Oculus Rift VR headset ships on March 28 with Unreal support.