While certainly creative, this game is overall rather bad.
For starters, the absolute lack of any tutorials, tooltips, or general indication of what anything is or what it does. I had to guess everything, including which tower was even mine! Nearly all of the difficulty comes from the lack of understanding this causes.
Secondly, the price of a unit increasing every time it is summoned is annoying. If I am buying a single unit I would expect the price to remain constant. If I was buying something that would generate units over time I would be okay with the price rising.
Furthermore, two of the three specials have the exact same effect as well as the price rising. I understand that one is slower than the other, but they still have no observable difference in effect. The only one with any difference from the others is the most powerful one almost purely because it's understandable to use.
Hopefully, you will take what I've said into consideration next time you try to make something. The most important thing a creator can do is learn and grow from the criticism they receive.