The instructions are clear, but you're asking me to pay a heavy cognitive price to parse them.
You have a lot of active keys. I think showing a keyboard, with the keys highlighted and explanations attached, would be easier.
The mechanical explanations are clear but quite verbose. Unless you're purposefully text-forward, I would condense all of this into an explanation of "here are values that kill you when they reach 5", and [item icon]:[effect icon][op][value] for the rest, like [cigarettes icon]:[madness icon]-1. So 2 cards altogether, + the keyboard.

To read the book, he just take, player needs to press 5 buttons. And first button (open menu) is not obvous for players who doesn't play these type of games often.
I think, it'll be a good idea, to make 'I' as hotkey for Inventory, and after taking book, show hint: "Press 'I' to open inventory..." or something like that. Anyway, inventory is an important part of the game isn't it? So, hotkey would be good idea.