I like the concept, but I found it hard to understand what was needed. I didn't have time to read the instructions for the second level before I died (maybe I had momentum?) and then how to change the colour wasn't clear. Could I only select the letters I could see? Did I need to hit them several times? Experimenting resulted in dying, and that's lessened the enjoyment.
All that said, if the controls were more clear, I'd love playing a version of this on my phone. I liked the way the levels changed and grew, and I loved the concept.