There's a small misspell in the text for the final boss. It says "This is THERE the Engineers and Iron Guards came from." I think you meant "This is WHERE...".
Displaying how many enemies got through your defenses would be nice. If some slip by without your notice and you're playing for 3 stars, it keeps you from playing through the whole level for nothing.
 "Cursed Treasure 2"){kind=icon}
 "Giants and Dwarves TD"){kind=icon}