For anyone interested in terrain generation and possible environments for characters Unity is a nice way to go about it. We've seen what the Unreal Engine can do lately and Unity haven't dropped the ball either.
Rather than repeat myself all over the web as I gush about this wonderful new asset called Map Magic, here's a link to my blog article where I barely scratch the surface. This is all realtime - it's amazing how far we have come. My article has a couple of short videos.
Oh and some pictures, we like pictures. :)
http://widdershinsstudio.uk/unity-map-magic/ (http://widdershinsstudio.uk/unity-map-magic/)
(http://i0.wp.com/widdershinsstudio.uk/wp-content/uploads/2016/03/Untitled-4.jpg)
(http://i2.wp.com/widdershinsstudio.uk/wp-content/uploads/2016/03/Untitled-1.jpg)
(http://i0.wp.com/widdershinsstudio.uk/wp-content/uploads/2016/03/Untitled-2.jpg)