Great game! It gets quite difficult quite fast. Maybe a way to move the camera around would be nice, because in this kind of games (you only get one resource, then your movement and interactivity is limited) you really need to know all the pieces of the puzzle before making your play, and sometimes you kind of end up having to die a few times forcefully by wasting the jump to see all the map.
Also, the tail collides with the boxes! i'm not sure if it's intended. Specially notable in the level where you put the two boxes in the hole with the spikes to pass through.
However the way you introduce the mechanics is top notch. Seriously. Well done there! you know exactly how everything interacts and get a grasp of the rules quite quickly.
Got stuck in level 11. The ladder jump is really hard!