This was fun. I've been making it a habit of commenting on submissions I find that rely on color recognition for its mechanics with suggestions about making it colorblind accessible. (I am colorblind, and I find that a lot of devs think about this basic accessibility very little). I will point out that, while the game relies on being able to recognize the color of the falling blocks, the color choices are good for avoiding issues for the common forms of colorblindness (i.e. the various forms of red-green colorblindness). I got a score of just over 70, and never felt like the color recognition was the limiting factor for me. I will say that, if this were a larger project, having the option to add symbols to the colors would be a good idea for general colorblindness accessibility.
As for the gameplay itself, I feel like this might have worked better if you had four buttons/keys that set it to a specific color each. I understand that the one-button thing was from the theme, but I don't see the added restriction as one that was used to make the game more interesting to play.