It's a start. Medal didn't work for me for some reason, but...
The challenges were nice. Though the true difficulty of the game came out of the controls, which really is a bad sign. in many situations, I just needed to move an itsy bit more towards a certain direction, but even if I tap an arrow key, it always does much more than needed. My suggestion: get rid of the death by contact with a wall. Just set the wall collision to stop the movement of the player. While it's nice to add difficulty through making wall = death, this is frustrating rather than providing a feeling of accomplishment after beating a level. Try adding difficulty through clever level designs. Also, it was difficult to control which direction the white shield block would be facing me. The gravity effect is nice here, but try to make it easier to control.