Good point. The only colours we have, where colour distinction matters is blue vs pink for the tokens. These are easily distinguishable because of difference in colour intensity (I don't know the technical term. But the blue is clearly darker than the pink). We have tested the game with more than 700 players over time using these colours and have never experienced a problem. There are colours for symbols as well, but here the symbols themselves can be used to distinguish between what is what.