Wow what an awesome game! You really established a nice foundation here that fits the theme well from a mechanical standpoint.
If I had to share some suggestions from my playtime, I would ditch using WASD altogether for movement. It feels like a game where the mouse would be handier (especially when your settlement gets really big). It was also sort of unclear how combat and conquering other settlements was to be accomplished.
Definitely a cool and unique approach to the jam. Congrats! :)