This tutorial will teach you how to create and use post-processing effects which simulate how colour blind players might experience your Unity game. One of my most anticipated games is The Witness; since it uses so many vibrant colours, it will be used as an example in this tutorial. This is how a player affected by red-green colour blindness (protanopia) might see it:

The image effect provided in this tutorial will help you understand which parts of your game are harder to see for color blind users.

Introduction

Colour blindness is a umbrella term that groups pathological variations in the perception of colours. Despite what the name suggests, the complete inability to see colours (achromatopsia) is an extremely rare condition. Almost three percent of the population has deuteranomaly, the most common form of colour blindness which affects the perception of green tones.

Normal – Protanope (red) Deuteranope (green) Tritanope (blue) Anachromatope (all)

When a particular colour receptor is missing entirely, we have protanopia, deuteranopia and tritanopia. When instead they are present but defective or in reduced numbers, we have protanomaly, deuteranomaly and tritanomaly.

Testing your game

The first step is to download the ColorBlind Unity package specifically created for this tutorial. Once imported in your project, drag the script called ColorBlindFilter onto your main camera. You can change the Mode to alter colours according to the different types of colour blindness.

There is also an additional option, called Show Difference. When enabled, it shows the game in black and white, adding a red tone to the areas that are more affected by the selected type of colour blindness.

The picture above shows which parts of the game are more affected by protanopia

Accessibility design

For most colour blind players, games that strongly reply on green and red can add an extra layer of challenge and frustration. It’s getting more and more common for developers to include a special option for colour blind users. FTL, for example, does this very nicely by ensuring that “no essential information is conveyed by a colour alone” (from Game accessibility guidelines):

This is possible even in games which are entirely based on colours, such as Hue. This upcoming 2D puzzle platformer has a colour blind mode which matches symbols to colours.