It's a very cool game,
the art style is nice, and the sound fits the game very well, the coin system is well chosen, yet, the moves/duration per match feel quite long, and the gravestone giving (only) one extra coin is not as useful when other units cost 3 coins, and since coins cant be saved within each round its sadly not working for me, I would think, that Items could be cheaper than units, but I'm sure, others that already beat the game fairly had a fantastic time. :) anyways overall good game.
For general key bind feedback:
Holding the left mouse button to "sell", feels quite off, until I figured it out it was a little late.
I would imagine a "sell button" that is shown somewhere could be way easier to understand.
The freeze unit button is useful, but if it would be only bound to the right click the left click could be reserved for drag and dropping enemies into place, I would enjoy it a bit more while being (for me at least) more intuitive.
I hope you don't see this as negative, more like just some suggestions from someone. :3
kind regards
JeckNoTree