"The pen must be broken": How a D&D game uncovered a rare disorder

The Dungeons & Dragons game master "Llewellian" shared a touching story on Reddit that highlights how a pen-and-paper game can do more than entertain – it can make a real difference. Llewellian regularly runs D&D sessions for kids and teens at a local youth center. During one session, he asked a new player, around 12 years old, to pick the "yellow guest dice." But the boy reached for a transparent set instead. Later, when the group was asked to trace their route on a white paper map using a bright yellow marker, the boy said, “Pen must be broken, no color comes out...” While the others clearly saw the line, he couldn’t see anything at all.

The game master responded with care and sensitivity. He paused the session and, in a playful way, tested the boy’s ability to recognize colors. It became clear that the child had trouble identifying certain shades. Without drawing attention to the issue, Llewellian switched to a green marker and carried on with the adventure. Later, when the boy was picked up, the game master quietly spoke to his mother and suggested a medical check-up. When the boy returned to the youth center, he shared that he had been diagnosed with a yellow-blue color vision deficiency (tritanopia). His mother had since bought him dark red dice with white numbers – much easier for him to see.

In the Reddit comments, many users shared their own experiences with color vision deficiencies – often discovered later in life, sometimes through school, video games or even during military service. Several recalled facing misunderstandings or even discrimination as children. Llewellian’s compassionate handling of the situation was widely applauded, with one commenter summing it up perfectly: “You are a great DM and a great person.”

The story also sheds light on the rare condition known as tritanopia, a form of color blindness where individuals struggle to distinguish between shades of yellow and blue. Affecting less than one percent of the population, it's more commonly seen in men than women. The issue becomes especially noticeable with low-contrast combinations – like yellow on white – where colors can appear faded or blend into white or gray. For educators, this is a familiar challenge: color vision deficiencies often go undetected and are discovered only by chance. Experts are therefore advocating for earlier and more frequent screenings, using tools like online pre-tests such as the Ishihara test. However, these are no substitute for a professional medical diagnosis.