The game is cool, but you should think about opportunity to play with differrent main heroes and races. Strygweers its a very interesting race for playing, but why only 1 mission with them? I wish if they buildings will appear more often in story, but in my opinion, they can be upgraded to full playable race.
Also, wish to see more neutral buildings that may give an some advantage and/or new units.
In total, one of the best idea for tower defence game I ever see. Great work:)