Cool idea and I loved the art style!
I think it would've made more sense if scaled down enemies had lower health. Right now if I run out of energy while I scale an enemy down, it just ends up being smaller and not weaker and I have basically wasted my resources.
And maybe add a little bit of background music in? I don't know, but with only the chirping in the background the game world feels a little bit... empty.
Also, I didn't get the "Increase view tower distance" power up for a while, and when I finally got it, I had already mowed down everything in view. xD