Color blindness effects a substantial amount of the population (1 in 12 for men and 1 in 200 women) worldwide. Many developers seem to forget this fact and by not having a colorblind mode in their game they risk alienating a rather large player base. This becomes especially detrimental if their game relies heavily on the use of color such as a puzzle game or perhaps a game that designates teams by the use of color. Companies like Blizzard, Riot and EA Dice have made sure to implement options that allow players who are color blind to modify the colors to allow for a more comfortable experience.
Example 1: Honey Bee Match 3 Edit
Honey Bee Match 3 is a simple puzzle game where the player must match matching colored honey bees. It's simple unless you are color blind in which case the game would be extremely frustrating if not impossible. The image below shows the original game and what the game would look like if you were green-blind. Keep in mind it is estimated that about 1 in every 100 people are green-blind.