I found the concept quite interesting, kind of a mix between a city builder and an idle clicker. My main suggestion would be to make the winning condition a bit harder. Right now you can build the castle almost right away, but if it required resources only obtainable through upgraded buildings, it would prolong the gameplay and make the goal more satisfying. I also really liked the minimalistic approach, it actually reminded me of a text/button-only city builder browser game I used to play as a kid! :)