I loved the implementation of the theme. It was pretty original. It was really cool that the background changed when the condition of the enviroment was different. The ending text was also great, because you got an incentive to play through the game a few times to see what would happen. 

I'm not sure whether the canon balls do anything. The lack of sound effects was also a bummer.

Really enjoyed this game! Great job!

acid rain being the good guy is an cool twist