Very cool! I like the concept of only being able to damage the enemy type of the area you are standing on! It's a fun mechanic that makes your game really unique!
Sometimes it is a bit hard to see the enemies when they are on the same colour, but only on the darker ones, especially blue.
I enjoy the endless mechanic, but found that once you get overwhelmed there isn't really a chance for a comeback, especially when you get more than 20 enemies or so, maybe a limit would be good or even a round based system?
I also found that eventually I was just in the abyss, running around with no colour and no way to find my way back.
Also, please add an audio slider, the music was quite loud.
But overall, a fun and well made game! Keep it up!