This is a fun little game with really nice mechanics. I like the big Help note on the side of the screen. The game bit slow in the browser, but I chop that up to how Unity builds for WebGL, I do recommend making a standalone build as well. The help board is simple enough to understand the basic mechanics at a glance; however, the stamps, excluding the good and bad stamps, might need a little more clarification or explanation on when to use them. The game has beautiful art, and I love the smoke effects when the characters disappear.
Edit: I initially played the game with hardware acceleration turned off, resulting in the game being a bit slow. Turning on hardware acceleration fixed this issue.