Colour-blind modes
Also said as Colour vision settings, Never colour alone, Redundant coding, Daltonism options
Settings that change a game's colours for people who see them differently, about 1 man in 12 and 1 woman in 200. The stronger rule goes with it: never let colour be the only thing that carries a meaning, and back it with shape, icon or position.
Red against green is the classic choice for enemy and friend, and it is the pair most likely to fail. A mode helps those who find it, whereas a second signal helps everybody from the first second.
Say it
“Enemies get spiked outlines as well as red. Run every screen through a deuteranopia filter before review, and if two things can't be told apart in greyscale, give them different shapes.”
Where you’ve seen it
Overwatch offers filters for protanopia, deuteranopia and tritanopia, with a strength slider. Hue, a puzzle game all about colour, has a mode that adds a symbol to each colour. Forza Motorsport's racing line is a warning: players report its red and green are hard to tell apart, the whole message of the line.
Not to be confused with high contrast mode
A colour-blind mode shifts colours so that they stay distinct. High contrast separates what matters from what doesn't, for people with low vision as well.