I liked the game. Was fun to play and as all tower defense games I want to make the absolute best tower defense! Was fun to play around and also nice idea with that upgrade system. I noticed also nice increase of difficulty once the defense is in place around 3 minutes.
Improvements I see:
- Adding music
- little animations for the mobs
- pause button
- options with volume sliders
- upgrades for existing towers
One bug I encountered is that sometimes the mobs kept moving if you have to place the upgrade. That unfortunately lost me the game. Any I had my fun and at least the “Under Pressure” place your tower very fast could be also an interpretation of it. :)
Good Job!