See the capabilities of the Unreal Engine 4 in creating complex visual effects.
Unreal Engine - Free
Today Epic Games have announced that their Unreal Engine is now free for all uses, with a 5% royalty.
Unreal + SpeedTree
Unreal Engine and SpeedTree allow for these beautiful outdoors shots to run in realtime.
Dynamic Lighting Gameplay with UE4 and Enlighten using Blueprints
Geomerics have posted a detailed article on how they used Unreal Engine together with Enlighten.