These aliens battle for specie supremacy. One specie is of the X race and the other is of the O race. Other than the marks on their bellies, they are identical.
There are 3 light sources in this painting. Yellow light comes from the upper left foreground, light blue light comes from the lower right background, and orange light comes from the laser pistol.
Since the main yellow lighting is a warm color, the shadows need to be a cool color. I chose purple for the shadows.
Since most of this painting is blue, in order to make the ZANG lettering stand out, I made it orange, which is the opposite color on the color wheel.