When the last piece of a puzzle like that is a literal puzzle, though, it’s even better. [Nadieh] has been working on this jigsaw puzzle that displays a fireworks-like effect whenever a piece is ...

So the more you can distinguish some pieces from others, the easier the puzzle. Where you do jigsaw puzzles is almost as ...

Some puzzles contain thousands of pieces to work with. The biggest in recent memory was called What a Wonderful World, which ...