The assets and music are quite good. Were they made by you?
The game UI also felt very solid. However, I had this issue where I could only create farmers. The icons for the others never turned blue. I guess this hasn't yet been implemented.
It would also have been nice to spawn in the vassals as you create them instead of it just being a background video sort of thing.
For 3 days of work, I think you've done a great job.
If you have time, checkout my game which is based on the same theme, though a different genre.