Epic Games has created award-winning series like “Gears of War” and “Unreal Tournament,” as well as a popular proprietary development platform. That platform, Unreal Engine, doesn’t only appear in Epic titles, though. The company has allowed other developers to license it — for a fee. Now, it’s opening up that platform to independent developers with no upfront cost. Unreal Engine has been used by some of the top developers in the industry, but Epic has been on a mission lately to expand its reach.