That's a simple concept, but the level design really shines ! I had to stop on some levels to think about a good order to do things, it's closer to a puzzle game than a platformer, I like it !
For the things you could improve, I think you could increase a bit the range of the attack, it feels way smaller than the slash effect, I often lost because of it. And the targets look like spikes, at first I thought I had to avoid them instead of attacking them.