Fun idea, this is my kind of take on the tower defense! Definitely on the easy side, doesn't seem to really ramp up too much but I had fun with it. A couple things I'd suggest:
- Make it easier to see all the towers, some were behind buttons.
- Make the customers leave when they run out of gold. I don't want any loitering in my shop lol
- Give me a better indication when all the towers are up, some kind of meter that fills up or a warning textbox
- Let me unpause with the same button I used to pause