Stars rendering was added to make the background more interesting. It uses a real star database of more than 100k stars. It will need some additional effects to make it nicer, like a halo around bright stars etc. There should be also an adaptive HDR to manage the large differences in luminance.
The terrain is quite dark at night even when sky is still lit, it doesn't take secondary scattering into account yet.
Something from another corner - the following image shows fractal blending of two materials and how it looks like from up close and from a distance. A similar approach will be used to blend land classes.
A quick hack of the terrain material system to make it like there is a snow on the mountains. The snow covers the surface if it is flatter than a critical slope, whereas the critical slope depends also on the elevation. This way the transition to lower altitudes looks better, although it still needs some tuning.
At the moment snow doesn't have any thickness, but later a build up of snow will be possible along with temporary tracks behind vehicles.
Last images, showing distant marked peaks and how they are visible against the background, viewed from altitude 7000m (~23,000ft):
The same view from 20,000m (65,617ft):