Pretty nice prototype. The gameplay could be enhanced more, especially the interaction with the boxes, and the level design, because there is so much space for the player to walk while the puzzles don't need all this space to be solved. Also don't forget about the camera movement.

Levels 4 and 5 were nice, while level 3 was a bit hard because of the enemies, and for level 6 more enemies should have been added to the (no) path, sorry but i had to find what was there :D. 

Keep going and have fun making games.