I liked this a lot but my one small critique is that your one-time ability to do infinite damage was mostly inconsequential in deducing the solution to a puzzle. In most cases it was fairly quick to figure out what it needed to be used on and it was basically irrelevant to the solving process from there.
That aside, I liked the simple visuals, and there were some solid puzzles. I especially liked the last puzzle because there were definitive problem spots that needed to be explored in depth and it was easy to experiment.
I also thought that the ending was cute. :)