Okay, I've never even heard of anything like this before, but I definitely like the concept. I used to play TTRPG games, and as I see it, this would be an awesome scenario to play out.
And the Appendix... I didn't read the whole thing because I'm lazy (English isn't my native language), but from what I did read, it looked like “how to write a book from scratch,” and I appreciate that.
Writing almost 40 pages must have taken a lot of time. Overall, cool stuff.