Great first attempt at a management game. Super cool. I agree with the person below the corners were too sensitive for the mouse, it got in the way of building. And I think a tutorial would have helped with how to build, assign buildings, etc...
Also, I think a progress indicator on the buildings, or a clock to let you know how long until the demons come would be helpful. I wasn't sure if they were coming, or if anything was happening a couple of times.
Good for you to try something new. Super inspiring. I think my next game might be a management game. Push myself to try something new.
Cheers!
- D