Great!
It really is a fantastic game, you should really make another one, but please make it go a bit faster. Some waves take 10 minutes to finish, and that's simply too long. Another thing, if you are going to make such a long game, please put in a pause button. If people are multitasking or have to do something while playing a game that takes 2 hours to beat, and they don't have a pause button, then they lose and have to start all over again, which sucks. If added that along with a few new upgrades like attacking speed or running speed, I'm sure this would make for an award winning game