Honestly one of my best pieces I've done. The color of the terrain might be a little bland but that it suppose to be because it's set in a desolace place.
The lighting overall is by using 2 different environmental light sources - Global Illumination and Ambient Occlusion with a massive redsky decay as the sun glare's close to the horizon.
I was planning to use Ray-Traced Shadows in the atmosphere to create sunshafts (volumetric light) but it didn't look too well with it.
Added a 3D Cumulus cloud layer to create the low ground fog effect.
Enjoy!