Epic Games is changing the business model for its next-generation game engine, Unreal Engine 4, giving users "access to everything" the engine offers for a $19 per month subscription and a flat, 5 percent royalty fee on game sales. The new business model for Unreal Engine goes live today and is aimed at "early adopters."

Tim Sweeney, founder and CEO of Epic Games, said the company has traditionally made its Unreal Engine available to large AAA game development teams at a cost of millions of dollars. But as the industry has evolved, Epic has had to "really rethink our whole business as to how we make the engine available to teams."

"Looking at the new shape of the industry now, we realize that's an outdated tool," Sweeney said. "Looking at the possibilities for the engine, we started from scratch and thought 'How can we make the engine available to more people?'"

With a monthly subscription, Unreal Engine 4 developers will get access to everything on Windows PC and Mac, and developers can create software for PC, iOS and Android platforms. Console support may come later, Epic said, after the company hammers out agreements with manufacturers.

"Everybody who subscribe to Unreal Engine 4 gets access to the engine's complete C++ source code," Sweeney said.

According to the Unreal Engine 4 website, subscribers to the engine will be able to cancel their subscription — or renew it — at any time. They'll be able to retain access to UE4 tools, they just won't be able to take advantage of the regular updates Epic has planned for the engine.

"People can come and go as they please," said Mark Rein, vice president of Epic Games. It will be on Epic to provide compelling monthly code updates and content to keep Unreal Engine users subscribed.

Epic will also have flexible licensing options for game developers and publishers who don't want to pay a royalty fee on gross game sales and would prefer an upfront flat licensing deal. Universities and schools, Rein said, will need to only purchase a single subscription.

Unreal Engine 4, under its new subscription-based model, is available today. Epic Games warns new users that the engine is "powerful, but not very polished, and it requires a beefy desktop computer." The developer outlines some rough areas, including Mac OS X and Android support and sparse documentation, saying "If you're looking for a more polished product, please check back in 6 months."