What Makes a Game Fun?

i was wondering, what are the factors intrinsic to the design of a game itself that make it more or less fun? It reminds me of my experience with jigsaw puzzles. For example, jigsaw puzzles are something ill admit or are addictive. But i would never classify putting a jigsaw puzzle together as fun. And if someone has a cool one'm all in. So there's something about and a jigsaw Puzzle isn't quite a game, but it lines up with some of the things that games are. What does that tell you about finding a game that will be truly fun for the whole family? Because that's something i do think about a lot nowt actively seeking out games that