Depending on who you get the statistics from, 1 in 12 or 4-8% of the male population is color vision deficient (politically correct term).  Oddly, the genetic deficiency is much more common in men than women.  The most common deficiency is the lack of red and green cones in your eye.  You could say that their vision is blue enhanced!   While color blind gamers might have problems coordinating their wardrobe, the more common problem is distinguishing who is on your team, which flag to capture or solve countless puzzle games which rely on the user to match up colored tiles or find colored jewels.  

So, what can game developers do?

The fixes are relatively simple to implement. Any time color-specific information is used as a game mechanic, give multiple options for those colors. A simple shift to different hues, or even a drastic increase in contrast between two colors would make these issues go away for color blind individuals. Patterns and shapes can also be used to great effect; a flag with wide stripes across it would be fix the issues people experience in games like Battlefield 2142.  

There is some hope.  Games like Hexic will let you turn on shapes to augment the colors.  Peggle Extreme has a colorblind mode that adds a triangle to the green pegs and a + sign to the purple pegs. GRAW has a selectable colorblind HUD with.  Games like Guitar Hero are easy to learn the fret positions rather than the colors while games like Audio Surf fail with its alternate mono-chromatic mode that does nothing to help the color challenged.  

Considering how many players potentially are inflicted by this condition, lets hope more game producers take this into consideration and  include subtle game design decisions that will make the games we play friendly for all.  If they dont, PC users will be forced to rely on their video card drivers to correct color vibrance.  

Source: Become a Robot,  ars technica