Great game, but the art design annoys the crap out of me. Why fill the screen with black and white? I lose track of my mouse pointer and character on a regular basis, on later levels. The game is difficult in a welcome manner. However, being able to see what the heck is going on is a poor choice for adding to that difficulty.
Know what would make this game less terrible? If enemies didn't have so much health that ramming them wasn't the best strategy. By the last level, the only thing you're using weapons on is turrets. The weapons are TOTALLY worthless, and trying to fight enemies costs more health from their bullets, and misses half of them anyway.
Almost a great game, but the balance is so out-of-whack that it just makes you want to punch someone in the face.
So ridiculously easy that the nice presentation just makes gameplay an even bigger disappointment. Beat the third boss without ever using a power, buying a tower, or even moving my whatever that thing is. Keep the cursor near the little bad-guy, and click until you get bored out of your mind--the end.
Halex let me know that I could pause it if I pressed spacebar (which I didn't know, cuz readin instructions is for suckas). Unfail to the game. Fail to me.