Great use of color shifting as a mechanic! Love the color scheme options as well, especially since I'm color blind!
At times, the shifting was only hard because my hand was trying to do too much at the same time.
My only suggestion, for what I was able to completed, is a simple accessibility functionality to allow both shift and ctrl keys to perform the color shift ability. Since you already allow both sides of the keyboard for movement, it would make sense. But also for those who are opposite handed and don't use WASD.