Anything that is difficult to understand or make sense of.
A game for one or more people that is more or less difficult to work out or complete.
A crossword puzzle.
A jigsaw puzzle.
A riddle.
The state of being puzzled; perplexity.
(transitive) To perplex, confuse, or mystify; to cause (someone) to be faced with a mystery, without answers or an explanation.
(intransitive) To think long and carefully, in bewilderment.
(transitive) To make intricate; to entangle.