I don't know if it's just my device, but there's an input delay to every movement that made it hard to control. I got stuck on the first lava pit in the tutorial because I didn't realize you could jump (the delay was so bad I thought jumping wasn't in this game). The second lava pit with the two metal grates was frustrating because my timing had to be perfect in order to get across.
The gun was fun to use. It responded to my clicks fast and was satisfying to use. The special attack felt great to fire although it didn't seem very effective at taking out enemies.
Speaking of enemies, they're small, incredibly fast, and almost impossible to see from a distance. I often got hit with bullets without understanding where they came from. Enemies are also hard to hit accurately, partly due to the extreme motion blur, lag, and their small size.
My advice: keep the gun, remove the motion blur, remove the input delay and make enemies bigger and slower. That alone should make it a lot more fun!
I also really liked the physics objects that I could push and shoot to move. Maybe you could experiment with a level that incorporates those as a main goal or mechanic.