This is a shot from my sci-fi horror webcomic, Promethean-1.
The dark environment is intentional... as there's a massive sequence happening in the underbelly of a colossal volcano.
I used pen-tools to draw the rover's outline... then filled in with colors in a painterly style. For the human running in front... I just used the brush to paint his form directly... no outlines.
I could share the layer-by-layer breakdown from PS on request. 
For this webcomic... I've actually tried to tone down my usual art style to ensure the story keeps flowing, and to maintain a consistent chapter upload rate.
