Unreal Engine is a complete game development framework for PCs, Xbox 360, iOS, and PlayStation 3, providing a vast array of core technologies, content creation tools, and support infrastructure content.
Every aspect of the Unreal Engine game development toolset has been designed with ease of content creation and programming in mind, with the goal of putting as much power as possible in the hands of artists and designers to develop assets in a visual environment with minimal programmer assistance, as well as giving programmers a highly modular, scalable and extensible framework for building, testing, and shipping games in a wide range of genres.
Website & download: http://www.unrealengine.com