Color blindness is an affliction that affects more people than we are aware of. It's estimated that between approximately 1 to 2% of men suffer from some sort of color blindness. When you think about it, that's a staggeringly large number.
Yet color blindness is almost never taken into account in video games, barring a few (very commendable) exceptions.
(Personally I'm not color-blind, but I do fully empathize.)
In most games it makes little difference because in them color is not a critical issue. In some cases it can be more of an issue (for example, in a mini-map different types of elements are depicted with symbols with different colors, such as enemies with red arrows and friendlies with green arrows.) In some games, especially some puzzle games, being able to distinguish between colors is completely crucial.
As a prominent example, Might & Magic: Clash of Heroes is an absolutely wonderful game (which I have played through three times, even though I very rarely play games more than once.) This is, essentially, a color-matching game (a bit "bejewelled" type, but with a fantasy setting). Its biggest problem is that it does not take color-blind people into account at all, and this causes real problems. (For example, on its Steam page there are threads made by color-blind people who find it very difficult to play the game.)
The game looks normally like this:
In this game you have to match fighters by color, by making vertical groups of three fighters of the same type and color. In the example image above, you would move the green archer on the left to the column with the two green archers on the right.
However, to a certain kind of color-blind person, the game may look something like this:
You probably can understand the problem. (And this is a highly simplified scenario. It becomes a lot more confusing when the battlefield is more full of sprites.) The game offers no help to alleviate this problem.
Video games very rarely take into account this problem, which can be really bad in these types of games, where distinguishing colors is crucial. I think this is something that video game developers should be aware of and take into account.