Colour blindness and accessibility

Colour vision deficiency, usually called colour blindness, means a player cannot distinguish some colours that others can. For game art, the main rule is that colour must never be the only way to tell the player something important. Microsoft's Xbox Accessibility Guidelines put it plainly: "Color alone should never be used to represent information" (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

#How common it is

The Game Accessibility Guidelines note that difficulty perceiving red or green is "very common", "affecting around 8-10% of males" (gameaccessibilityguidelines.com: Ensure no essential information is conveyed…). It quotes Karen Stevens of EA Tiburon: "We estimate that over half a million current Madden NFL users are colorblind" (gameaccessibilityguidelines.com: Ensure no essential information is conveyed…). The guideline is rated Basic, the level every game should meet (gameaccessibilityguidelines.com: Ensure no essential information is conveyed…).

There are several types. The Xbox guidelines name deuteranopia ("a common form of colorblindness"), protanopia and tritanopia, and stress that because of "the many types of colorblindness and vast spectrum in which they can affect a person's vision", the goal should be that no key game element relies on colour alone (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

#What it means for environment art

Environments carry information too, not only the UI: team colours, climbable ledges, hazards, interactable objects, objective lights. The Xbox guidelines give the classic failure: enemies outlined in red and allies in green, which players who cannot tell those colours apart "will be unable to use" (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

Their fix is a second channel: anything critical "also needs to be expressed by using at least one additional signifier such as shape, pattern, iconography, or text labels" (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…). For a 3D artist, the strongest second channels are:

• value: a hazard that is much lighter or darker than its surroundings reads even with no hue at all.
• silhouette and shape: a climbable ledge with a distinct profile, or a team base with its own architecture.
• Pattern and texture: stripes, grates, chevrons, or wear patterns on interactive surfaces.
• Light and motion: a pulsing emissive, a flicker, or particle effects. See emissive materials.
• Sound, which the Xbox guideline covers alongside visuals (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

#Colour-blind modes or colour-independent design?

#Testing

Simulate early, then test with people. Unreal's same node can simulate a deficiency: with correction on, "you can use this to visualize what the correction looks like with the deficiency" (Unreal Engine Documentation: Set Color Vision Deficiency Type); Epic's API lists the deficiency types as an enum, EColorVisionDeficiency (Unreal Engine API Reference: EColorVisionDeficiency). Both guideline sites recommend the free desktop simulator Color Oracle (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…; gameaccessibilityguidelines.com: Ensure no essential information is conveyed…), and Xbox also lists the Colour Contrast Analyser (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

But the Xbox guidelines are clear that "Simulation filters or other simulation tools shouldn't be used as a replacement for testing with actual players with colorblindness"; they are an internal check "before user testing" (Microsoft Learn: Xbox Accessibility Guideline 103: Additional…).

#Related pages

colour for environments · value · visual hierarchy and readability · signifier · affordance · wayfinding · silhouette · emissive materials

#Further reading and watching