Wow, awesome idea, reminds me alot of the game "Castles" of the shitty mobile collection "2 Player games free". If you don´t already know it, check it out, because i was looking for a good version of it for a long time. And here i have it! For some feedback tho:
1. I unfortanetly don´t know how "attack" and "coins" work. Also i don´t know how to get more population. Maybe i´m just stupid, but make that more clear in the tutorial.
2. I liked the graphics, but maybe zoom out a bit more so that you have an overview.
3. Just polish it a bit more in general. I could DEFINETLY see this as a full game with several levels, or even better: A multiplayer RPG were you can select different characters and stuff. I would love that. Also, what is that font, i like it. :)
I hope the feedback helped you, would be nice if you could check out my submission too. :)