puzzle
noun
°Anything that is difficult to understand or make sense of.
"Where he went after he left the house is a puzzle."
°A game for one person that is more or less difficult to work out or complete.
verb
°To perplex (someone).
synonyms: anybody's guess, anyone's guess, conundrum, enigma more» , mystery, brain-teaser, poser, crossword, crossword puzzle, jigsaw, jigsaw puzzle, guessing game, riddle