Light

Dead Space concept art

The main light source in the image is strong torch light but most of the image is in shadows.
The silhouettes of the monster in the  background are hard to see so that they can still be threatening even in concept. There is also light coming out of the helmet but it only lights up a small area due to its size. Most of the image is actually light reflecting off of the armor being worn by the main character which i think is really clever.

Fallout 3 concept art

The main light source in this image is strong sunlight and casts large shadows over the area. There are also little light sources coming from the ship. I really like this image for its strong colouring and different shades of brown.