Loved the usage of the limitation in your game, it was really smart!
I didn't get to use the magenta ink, I might have missed something because I didn't know where to press to use it. Chaining the yellow ink for an additional effect was cool but setting up that chain reaction is a bit hard.
Overall your game is really fun and enjoyable but it also felt easy. I only used the cyan ink to get through the stages. If I painted a large enough area it would make it easy to kill the enemies before they reached me.
Great job and keep it up!