PaneSlide is a game about colour, so it matters that everyone can play it, including the many people whose colour vision works differently. This guide explains how colour vision works, what colour vision deficiency (often called colour blindness) means, and how PaneSlide's Patterns setting helps.
How the eye sees colour
At the back of the eye, the retina has two main kinds of light-sensitive cell:
- Rods work in dim light and do not distinguish colour.
- Cones work in brighter light and give us colour vision.
Most people have three kinds of cone. One kind is most sensitive to long wavelengths (towards red), one to medium wavelengths (towards green), and one to short wavelengths (towards blue). No single cone "sees" a colour. Instead, the brain compares how strongly each kind responds. Yellow light, for example, excites the long and medium cones strongly and the short cones very little.
This three-part system is why three light primaries can make so many colours on a screen, as the primary colours guide explains.
What colour vision deficiency is
In colour vision deficiency, one kind of cone works differently or is missing. The person can usually still see colour, but some colours that look different to most people look similar to them.
The main types are:
- Protan (long-wavelength cones affected) and deutan (medium-wavelength cones affected). Together these are often called red–green colour vision deficiency. They are by far the most common.
- Tritan (short-wavelength cones affected), sometimes called blue–yellow. This is rare.
- Complete colour blindness, seeing no colour at all, is very rare.
Inherited red–green colour vision deficiency is commonly estimated to affect up to 1 in 12 men and 1 in 200 women. It is more common in men because the genes for the long- and medium-wavelength cones are on the X chromosome. Many people are born with it, but the NHS notes it can also start later, for example with some eye conditions, other illnesses or medicines. Most people adapt well to seeing colours differently.
How it is tested
The best-known test is the Ishihara test, first published in 1917 by the Japanese ophthalmologist Shinobu Ishihara. It shows circles of coloured dots with a number hidden inside. People with typical colour vision see the number, while people with red–green deficiency may see a different number or none. Opticians use it and other tests to check colour vision. The NHS notes that colour vision testing is not part of the routine NHS eye test, but you can ask an optician for one if you are unsure about your own colour vision.
Which PaneSlide colours can be confusing
PaneSlide uses cyan, magenta and yellow glass, and the mixes blue, green, red and black. Depending on the type of deficiency, some pairs can be hard to tell apart:
- With red–green deficiency, red and green mixes, and sometimes magenta and blue, may look similar.
- With the rarer blue–yellow deficiency, cyan and green, or yellow and white, may be harder to separate.
Everyone's experience is different, so these are examples, not rules.
The Patterns setting
PaneSlide has a Patterns switch in Settings. When it is on, each glass colour gets its own texture as well as its colour:
- Cyan glass has diagonal stripes.
- Magenta glass has dots.
- Yellow glass has horizontal lines.
Patterns are drawn on the panes and on the target picture. When panes overlap, their patterns combine, just like their colours. A cell with dots and horizontal lines is magenta + yellow, which is red, whatever the colour looks like to you. Black cells show all three patterns.
That means you can solve every puzzle by pattern alone if you want to. Many players with typical colour vision also like Patterns on the busier boards, because it makes overlaps easier to read at a glance.
Other help in the game
- Colour names for screen readers. Each pane is announced with its colour, such as "Cyan glass", along with whether it is locked or one-way.
- Mix labels. The first time you make each new mix, a small label names it, such as "Cyan + Yellow make green".
- No timers. There is never a rush, so you can check a cell as carefully as you like.
The accessibility guide lists all of PaneSlide's accessibility features.
Tip. If you find two colours hard to tell apart, turn on Patterns and look at the target picture first. Reading the picture by pattern is often quicker than by colour.
Sources
- NHS, "Colour vision deficiency (colour blindness)" (causes, Ishihara and arrangement tests, testing at opticians), checked 29 October 2026.
- Wikipedia, "Color blindness" (protan, deutan and tritan types; prevalence up to 1 in 12 males and 1 in 200 females), checked 29 October 2026.
- Wikipedia, "Ishihara test" (Shinobu Ishihara, 1917), checked 29 October 2026.