It is a mystery, and the narrator keeps you guessing. Isn't that the point? Sure would be a shitty book if the narrator told you right in the first chapter....what would be the point of finishing the book?

The point of a mystery is the author drops hint(s) in the book, so that looking back you
can see, Oh, yes, that would indicate that so-and-so did it.

As opposed to dragging something in at the last minute, Oh, I forgot to tell you that I did it.

I have to admit that I have not read any books in this style, or I don't remember reading any. So maybe it doesn't work well. So, are you saying that there are no clues along the way, or that most people ignore them because they never expect the story teller to be the culprit?

And I've already returned it to the library, but no way would I go back and look for such clues.

But to me it's kind of like the dream trick. Where all this is happening to somebody and they woke up and ---voila, it was only a dream!

(Yeah, I know Lewis Carroll did it, but that was a long time ago, and a children's book.)

I don't remember seeing it in literature other than that, but I've seen it in grade B- movies.

The original novel like this was an Agatha Christie novel, The Murder of Roger Ackroyd originally published in 1926. When I finally got around to reading it some years back, I was about halfway through when I stumbled across something or another that gave away the plot. Damn! It's the ONLY time that's ever happened to me.

It's still a novel worth reading.

I think your problem is that everything after is a pale imitation. Try reading the original.

if things are revealed bit by bit that shows that the narrator is unreliable. The whole thing turns into a "can I trust what's being said is actually so."

We rarely give flesh-and-blood humans unlimited credence. We just do it more readily to narrators in books.