Games should be based on mechanics that are inherently fun. "Click this thing as fast as you can" isn't. It doesn't belong in games. If you want a tradeoff between "place units" and "make money," make it so you hover over the book to speed them up. Also, units should have a range indicator when you place them.
So I'm a piece of poo that breaks ice? Has a few control issues. When you hit space, the guy always winds up facing down, which matters if you want to destroy then re-create the blocks. Shooting shouldn't affect the way you face. Also, he doesn't move immediately when I press an arrow key. In a game about avoiding enemies, that's a problem.
When you get to town you can buy upgrades with coins. And play poker. But the poker is terrible, it takes so many clicks to deal, and raising doesn't work like it should (you only raise once, and your opponent can't fold, so you should always win).
2/5 due to controls (you move slowly when you're close to the mouse). Would change the rating once the controls are fixed. Hope that happens while this is still on the front page, before it gets lost in the sea of 3-star-and-below games.
Main screen -> Options -> Controls, there you can change them to what works better for you. I hope it helps.