Ellipses
This article describes how the elliptic body parts in Ecstatica are rendered.
Shademap
In the Ecstatica data files there's a small nifty file called "shademap.dat". Let's have a look inside:The left figure shows the color-channel of the shademap, the right figure shows the z-channel of the shademap


The greyscale color values shown in the left image are mapped to a appropriately colored palette. The background of the sphere in the left image has color values >= 128 so this is propably used to mask the background.