Some things I have noticed immediately after launching the game:
Disable/remove any "Exit" buttons for the web version of your game. All it usually does is freezes your game or turns it into a black screen.
As some people said, game doesn't scale with window and book covers only like 1/4 of the already small screen, making it unreadable.
Attack animation is barely noticeable (also why would a wizard swing his staff like a melee weapon?)
I think I could damage and kill things through the walls/fences.
I'm not sure if the game fits the theme at all? I guess it might have something about trust written inside the book?
Still, many people probably didn't even submit their game at all, so congrats on joining the game jam! (21 seconds before deadline is diabolical )