Page "Unreal Engine" Paragraph 30

While the Unreal Engine 3 has been quite open for modders to work with, the ability to publish and sell games made using UE3 was restricted to licensees of the engine.

However, in November 2009, Epic released a free version of UE3's SDK, called the Unreal Development Kit ( UDK ), that is available to the general public.

According to the current EULA, game developers can sell their games by paying Epic the cost of $ 99 USD, and 25 % royalty on UDK related revenue from all UDK-based games or commercial applications above US $ 50, 000.

The December 2010 UDK release added support for creating iOS games.

As of the September 2011 release, iOS, Mac OS X, and Windows platforms all support UDK-created games.