Blocked out first: a rough solid whose horizontal section is a rounded square, so it has a front, two sides and a definite corner between them. Every plane gets one flat tone off its real normal. Then the features are drawn on top — an eye is two arcs and a pupil, a nose is one long curve around a tip. Flat like a 2D drawing, because there are no gradients anywhere; solid like a 3D one, because every tone is computed. Press listen and it will explain itself, over music that is also just code.