Free Unreal Development Kit

Nvidia announces the release of Unreal® Development Kit, the free version of the award-winning Unreal® Engine 3, the software development framework used to create computer and video games, 3D simulations, TV shows, films and more.
Of course, free for non-commercial projects. If you plan to earn money with your project, then check the licensing terms. Expensive, IMHO, but not as the elder brother used in almost every major title released in the last 2 years.