An excellent game. The only complaint I have is that the badges are a bit too easy for their respective levels. Completing Module 3 for 5 points and Module 5 for 15 points seems a bit more fair.
Once the boss is outside the range of one of your towers, just throw the gem at him. That's how I survived the level. 2 Level 6's FTW. Water trenches help a lot too, I'd recommend 5 or so in a row.
Dexter Dog's comment is not only extraordinarily politically incorrect, it's also one of the greatest quotes of all time. By the way, the game was terrible.