I have a big problem with bosses on nightmare. They seem to kill me when I have over 100 healh. According to the game they did less than 50 damage. considering this happens reliably it is quite annoying. Nice programming there guys.
I see alot of people complaining about the ghost bug, well don't forget about the splitter glitch that pushes little bubbles through the cracks of your towers right at the end of a long stage.
 "Dawn of the Dragons"){kind=icon}
 "Bubble Tanks Tower Defense"){kind=icon}
 "Drag It!"){kind=icon}