Epic Games

SAN FRANCISCO -- In a pivotal shift in how it licenses its massively popular and widespread game engine, Epic Games has made the next-generation version of that software, the Unreal Engine 4, available to the public as a subscription-based service. It will cost $19 a month and will involve a royalty agreement asking for 5 percent in gross sales. The engine is available for download today.

"We've always made this available to AAA game developers -- costs many millions of dollars, involves negotiating for weeks or months at a time -- but for the very big teams that have wanted access to it, they've been able to get it and build some really great games," Tim Sweeney, Epic Games founder and technical director, said at an event held at the 2014 Game Developers Conference here on Wednesday.

"How could we make the most valuable and useful engine available to everyone as practical as possible? We came up with an entirely new business model for the Unreal Engine," he added.

Game developers can still negotiate custom terms that involve heftier upfront fees. If the game is free-to-play, Epic will still take 5 percent of any microtransactions and ad revenue. If it's completely free and made for fun, there is no royalty agreement.

"You get access to everything: the unreal editor, for PC and Mac, and on those platforms you can then deploy to iOS and Android. All those platforms stay and more are coming in the future," Sweeney said.

Epic also is releasing the source code of the Unreal Engine 4 in the hopes that it will foster a community of tinkering and manipulating and user development.

"The source code is Epic's crown jewel. The entire code base we use to make all of our games -- the entire code base we make available to the licensees who pay millions," Sweeney said. "Absolutely whatever you want, you can find it in the Unreal Engine 4 today or you can find it out in the Unreal Engine community or you can build it yourself." Epic is releasing the source code for the engine through GitHub.

In a lighter moment, Epic showcased a unique feature of its engine: the ability to build games within games with ease and near-zero C++ knowledge. To do this, the company unveiled a game, built in two days by someone without C++ skills. Naturally, it was a Flappy Bird clone.

Photo by Nick Statt/CNET

"I doubt he was even sober for most of the time he was building it," Sweeney joked of Tappy Chicken. The clone was constructed within the Unreal Engine 4, meaning one can manipulate its mechanics in real time, either while playing or in simulation mode -- a pivotal feature of the engine from a development standpoint.

The shift for Epic comes at a complex time for the industry, where the creation, monetization, and growth of games has long been upended by mobile, free-to-play, and social-fueled browser titles.

In that vein, Epic's insistence on bringing the Unreal Engine from AAA studios down to the everyman is as much a chance to capitalize on a lucrative and explosive market -- thanks to that all-encompassing royalty agreement -- as it is a defensive maneuver against growing, multiplatform engines like Unity.

Just this week, Unity announced a partnership with Mozilla that allows Unity 5, the company's latest engine to be released later this year, to be implemented plug-in free on the Web, making it a tool for building a stunningly diverse set of games, from HTML5 mobile browser games all the way up to high-end AAA console titles. Unreal did the same, yet Unity's aggressive expansion, and good standing with Sony and PlayStation developers, is putting pressure on the engine race.

Sweeney is well aware of that. "We're aiming to wipe the slate completely clean," he said. "That's a bold, new step for Epic, but we think it's an appropriate one given the new style of the industry. It's an open and democratic form."

With Unreal Engine 4, Epic is making a play to make sure it stays a front-runner with the big names and blockbuster titles, but also a tool for the indie developers and smaller studios now remaking the industry from the ground up.