Making your entire design a puzzle leads to a reader to ponder about just what the book is going to be about. Typography interacting with true world objects is very popular at the moment and we can see the guy to the cover getting used since the ‘I’ in ‘Liar’. https://www.tumblr.com/selfpublishonkindle/791729642725834752/maple-publishers-expert-self-publishing-london?source=share