Just Fit

Posted on by Gabriel | 0 comments
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(Click to Enlarge)
Just Fit, also called Devil's Chess, was designed by William Strijbos and won the Hikimi Puzzle Competition in 1990 (competition for wooden made puzzles only).

The puzzle is entirely made of hardwood with two contrasting colors that give it a great checkerboard appearance. Comes with a nice sized tray, measuring 12 x 12 x 4 cm (4.7" x 4.7" x 1.6"), and there are 16 pieces. Each piece is made out of two colors, and they represent all possible ways to have the tops cut at an angle. They can be joined together to form a two layer 4x4 checkerboard, but for that you need to follow a specific rule: The pieces must be joined only with opposite colors. In other words, the bottom layer starts with a white square in the top left, while the top layer starts with a black square in the top left.

(Click to Enlarge) - The 16 Pieces

There are many ways to join the pieces together (see a couple of examples below), but almost all of them will result in failure. This extremely hard puzzle will test your packing puzzle skills to the limit, but a fair share of luck might be needed as well. With 16 pieces, each with two parts that have cuts in four possible directions, you can imagine the number of possible *wrong* arrangements.

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My first attempt was to check for matches in the pieces two at a time, but I couldn't get all of them to match, always leaving one or two pairs without a possible connection. Another attempt was to try and fit the pieces four at a time, two at the bottom and two at the top, but with layers perpendicular to each other. Again, I was left with a couple of unmatched pieces. With already two unsuccessful attempts, the solution was starting to look all but straightforward.

My next strategy was to just lay out all the eight bottom layer pieces in a non-linear way and then, get the top layer pieces in a sort of random arrangement. I say "sort of", because if you're just laying out pieces completely at random, you might be doing that for a long while. When you start packing the top layer pieces, or even when you're still at the bottom layer, you need to check for incompatibilities with the remaining pieces, as there might be combinations that will not be possible to match. For this, I say "sort of random", like a controlled chaos.

I also mentioned above that a little luck might be needed, and from my experience that may be the case. Since you have to make a few random choices at the beginning, although you might be able to correct them afterwards, you at the mercy of luck for the following pieces to fit. I lost count to the amount of time I needed to solve the puzzle, but I reckon that it must have been more than two or three hours, combined in multiple sessions. A few days later, I scrambled the pieces again and until now, I wasn't able to solve it again. I'm not sure how many solutions are there, but I believe it might be more than one, mainly because of the high number of ways the pieces can be joined together.

Update: I was informed by the designer himself that there is indeed more than one solution.

(Click to Enlarge)

Closing Comments:

Just Fit is a very interesting concept and great looking puzzle that shouldn't be missed. Some of William's most popular puzzles are made of metal, so it's nice to see a wooden puzzle for a change. Packing puzzle fans will love the puzzle, and even though it's a hard puzzle, anyone can try to solve it.

Availability: The "Just Fit" puzzle came from Brilliant Puzzles, but as of the time of writing it's out of stock. You can check at another time to see if it's available again or you may want to try and contact the designer directly and ask for a copy.


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