It’s something that we don’t really think about…there are people that are just color blind. For someone that’s color blind, a game can really be difficult to play if certain colors are put together, and color is a big factor in games. It occurs in males more (up to 7% in some countries) and far less so in females (less than 1% typically). While that doesn’t sound like a big number, the translation to actual numbers comes to about 10 million men in the US.
But some games accommodate for this by not only adjusting color contrasts, they use strong iconography so that color doesn’t need to be a factor. Bungie just announced that in the next Destiny update, they will be a color blind mode that adjusts the contrast of the game so that color blind gamers can play without trouble.
Bungie highlights this in their newest update.