When it comes to describing something as mysterious or unknown, there are a variety of synonyms that can be used instead of the phrase "more mystery." Some examples include an enigma, puzzle, riddle, conundrum, or perplexity. These words all convey a sense of confusion or uncertainty, but each has its own unique connotation. For instance, an enigma suggests a deep and complex mystery, while a riddle implies a problem to be solved. By using different synonyms for "more mystery," writers can convey a sense of intrigue and suspense in their work, making it more engaging and compelling to readers.