Following the completion of my Dyad demo in a darkened hotel room, I was informed by developer Shawn McGrath that I had likely just experienced synaesthesia. He asked if I'd heard the music change when the visuals abruptly changed, which I had. He then told me the music didn't actually change, meaning that I'd heard the visual effects. My senses had become tangled.

McGrath said this was an unintentional side effect of the way he designed the last level (which he had skipped ahead to show me). Without spoiling it, I'll say that Dyad's ending is a protracted sequence of total visual hypnosis, interrupted only by my pause halfway through to wipe my eyes. Turns out I hadn't been blinking and my eye became irritated and watery.