First of all thank you for really taking the time with this, it's a serious project of ours so it means the world to get concise feedback when we had so low a sample to pull from!
I'll be adding your specific feedback on the overall pacing of the game and some of the individual improvements you suggested which are in-line with what we had planned next.
This was a prototype and we'll be really kicking into production soon with a stronger approach to enemy theming and digging more into the upgrades tree. I'll for sure to update this page when we get more info to share or another build. Cheers
-Jay, Ded Dev Games