Unique take on the theme, but I had to play without fullscreen and set my scale to 100% (Instead of 150%). If not the UI elements would overlay each other.
150%:
Fullscreen:
I know the problem, but in the remaining time i didnt know how to balace it. The first waves are very hard, but with the right strategy they are very easy (maybe a bit to easy), so i think its an ok balance, but after wave 10 or so it gets too easy. I might come back to the project and will keep the Idea with the money at the end of a wave in mind.