I made something similar a while ago. I opted for calculating a score based on the sum of distance between each of the channel values and gave users one guess.

I made something similar a while ago. I opted for calculating a score based on the sum of distance between each of the channel values and gave users one guess. https://lukew3.github.io/color-code-tutor/ https://lukew3.github.io/color-code-tutor/