See the feature highlights for the Unreal Engine 3 from GDC 2012.
Unreal Engine - Free
Today Epic Games have announced that their Unreal Engine is now free for all uses, with a 5% royalty.
Substance in Unreal Engine 4 Tutorial Series
Allegorithmic have created a tutorial series that covers how to use Substance with Unreal Engine 4.
Real-time Global Illumination with Enlighten and UE4
Epic Games and Geomerics created the video to highlight the latest physically-based lighting techniques in games.