I'm glad you enjoyed it and thank you for the detailed feedback.
I agree on the lack of tutorial. The original plan had the priest guide you through, but because I ran out of time I ended up with just that letter-style message at the start and made the chickens give you various tips about the game, some more useful than others.
The NPC's are quite simple. The base that all NPCs extend from is only 80 lines of code, dealing with navigation, taking damage and death. The heroes are the only ones that have more complexity in the form of a spaghetti code that defines their routines and how to transition, because writing a handful of if statements on Sunday afternoon was faster than remembering how to do behavior trees :)
I do plan to turn this into a more complete game.