I love the artwork, and I never would have guessed the palette was limited for any reason. I could imagine playing this for hours on end, though I'd like to see more variety to keep it engaging.
I had a few audio issues: one of the sound effects was a little too loud, and the gameover sound came out very distorted and crunchy-sounding, as if the waveform was maxed out and then normalized (I'm not totally sure how to describe it).