Jigsaw Puzzle Design: It's about being able to predict what pieces fit

I recently had the pleasure of putting together a wooden jigsaw puzzle. It was so much more fun than the old cardboard puzzles. I got to thinking about why cardboard puzzles suck and thought I could do a little analysis for you. 

Ravensburger puts out like a million of these

mini Japanese puzzle has even fewer piece types

This is from your typical cardboard puzzle. There are about six major piece types, and some rarer border and corner pieces. Since all the pieces look the same, you are pretty much stuck to looking at the colors on the pieces for figuring out where they go (oh, and the border-first thing). Having fun with this kind of puzzle relies heavily on having a diverse puzzle-picture, and having access to that picture. 

Wentworth puzzle

These pieces are from a puzzle I picked up in England. Since each piece's shape is very different from the others, it's possible to build this kind of puzzle by looking at the shapes alone. There are edge pieces, but some middle pieces also have straight edges. The pieces are wooden and have a satisfying feeling of fitting, unlike cardboard pieces where the cardboard gives a little even when you're putting together pieces that fit. There are still some conventional shapes, for which you can usually guess which way is up. Little "whimsy pieces" are shaped like things and it's easy to tell which pieces fit around them (for instance, you can see the silhouette of the horse-rider's head in one of the pieces here). 

the border is scalloped. This is a corner taken apart.

 This last puzzle I found the most devilishly clever. The pieces are all unique shapes, but they're similar in shape and are completely unpredictable in their orientations. Even the pieces surrounding the whimsy pieces weren't immediately apparent. For this reason I found that I was using all the available clues--shape, color, texture, whatever. It was even more satisfying to look at a piece and know it was exactly the piece I needed, before fitting it in (this rarely happens when I put together cardboard puzzles).

This moment of epiphany, when I could see the solution before enacting it, is crucial to a good puzzle game. It's the same feeling I get when I play falling-block games or things like Portal and Catherine. It's what makes puzzles fun for me. 

piece orientation is unpredictable. Artifact Jigsaw. 

Another aspect of jigsaw puzzles is that I've liked is that they're easily multiplayer. If someone else sees you working on a jigsaw puzzle, they can instantly tell how far you are and what kind of puzzle it is. Piecing together a puzzle isn't timed, and it's cooperative. You can start without having to wait for it to load and play for as short or as long as you like (if you're willing to re-do your puzzle). I haven't really found a puzzle game that's as good at multiplayer as a good old jigsaw puzzle.