According to Psychophysics of Vision by Michael Kalloniatis and Charles Luu, about 8 percent of men and 0.5 percent of women have some form of color blindness. This is a significant number of people (most of them are males because of gene mechanics), many of them can become your customers. You should take care of this category of players, which is much easier than you can assume. The following figure shows the players with different types of vision:
I think it is more correct to use the term color vision deficiency instead of color blindness, because people with different forms of color vision deficiencies basically do see colors, they have no black and white vision, based on shades of grey (except for a very rare disorder called achromatopsia). But they have difficulties with some of the colors and relative shades; for them there is a shift in the spectrum for specific colors. Color receptors give a response closer in hues to other colors, which creates trouble in perceiving...