The weird part of those pics is that Outerra looks much better than that and has for several years and in Outerra the whole world looks like that
Outerra looks like it does because all of the detail is fake.
It uses a perlin-based noise to generate low-level terrain detail from a very rough (probably ASTER) DEM model.
There are merits to both approaches, and ideally the future wild yield a fusion of the two.
