It feels and looks well-polished. Good job overall.

Thanks for including the how to play section; that was very helpful in understanding the rules of the game. I think a breakdown of each of the unit type's abilities would be similarly helpful. I was able to get a gist of how they worked by playing the game, but a dedicated written section on what each of them did would have been nice.

I can't say for 100% sure because of my limited time playing the game, but the units that attack entire rows/columns seem like they could be overpowered. That's a lot of potential castle conversion per turn.

Also, some victory fanfare at the end when a player wins would have been nice.