Very fun and polished game, I thought it was cute that the enemies are little hammer dudes.
The graphics and sound (I think the ballista was voice acted?) were great!
I got a bit stuck at the beginning, for whatever reason placing the structures inside the moat was the last place I expected you to be able to put them (thought it makes perfect sense now) - and also if you don't cover all sides at the beginning you might just lose immediately.
Great game overall!