Game is broken. You would think upgrading your weapon over 8 times would turn the 2 shot enemies into 1 shot, but nope, does nothing. I like the idea but the game sucks.
I made my goal of a million the other day, haven't had any urge to keep going. Good game but it just drags on after a certain point because upgrade prices double yet the upgrades themselves are very small each time. So it gets to the point where it takes forever to get enough money just for a tiny upgrade. I think you should've made them a bit more substantial as you upgrade more, or at least make money a little easier to get so it doesn't feel like such a chore. And you should add in special things that give you an advantage for reaching absurd heights.