Skydome rendered with Terragen: A large sun shines through a dense murky green atmosphere resulting in weak soft shadows. The sun itself is not green and will produce neutral direct illumination, most evident in shaded areas such as interiors lit through a window. In open areas the bright atmospheric glow around the sun adds bright but diffuse directional lighting. The combined effect gives the appearance of green tinted sunlight.
Try a low background strength for a spooky moonlight effect.
Lowered horizon and stylised ground viewed from a standing height of 1.7m but not obvious if seen from higher.