As much as I like the artwork for the environment, I felt that the characters were out of place here. Which is something you should really look out for, when doing artwork for games.
Some platforms were either completely unnecessary to place on the level or were a little uneven. For instance, on level two I had to activate a switch in order to open a door. I had to use one of my characters to increase their height so the other one can flip the switch. However, I also had to do this while on a staircase which felt really uncomfortable.
The concept is pretty cool, and does a pretty good job with relating to the theme. I just think the puzzles and platforms need a bit more work here, and change the artwork for the characters.