It took me forever to figure out what this book was called! I read this in middle or high school, and recall being pretty disappointed in it at the time, but it did also make a pretty big impression on me in that it introduced me to the idea of tabletop RPGs.
So, keep in mind that when I was a young'un, the internet was still young, and didn't contain everything yet, and also even if I could have found things related to RPGs, I didn't know what I didn't know. There wasn't a very strong culture of social media, so even if it was on the internet, you still had to know what you wanted to look for. On top of that, a lot of us didn't have regular internet access yet, so it was unlikely to just stumble across things. So I do still think fondly about this book in that it's the reason I learned about RPGs and decided I was interested in the concept. This later led me to some great times with my high school nerd friends.
However. The book itself was disappointing. I mostly didn't care too much about the real-life aspect, and while the game part was initially kind of fun, the story got weirdly biblical after a while. I don't even remember ultimately what happens, except that the bible aspect just doesn't go away and I think the game aspect gets less fun and more plot-device-y as the book gets closer to the end.