Zig-Zag Knot. Thanks Tanya!
This puzzle is following on the success of Gordian's Knot after Gordian's Knot showed that a difficult burr could indeed be successful. Designed by Ronald Kint-Bruynseels, Zig-Zag Knot is a unique variation on the classic board burr. Rather than having flat pieces like a board burr, the pieces are shaped like Z's with the ends bent. This complicates the interactions between the pieces, since the shapes tend to interfere with each other.
It took me about 20 minutes to get it apart, though the first time I did it I used a rotational move to remove one of the pieces. This is not necessary and shortcuts the solution somewhat. Removing the first piece is probably the biggest challenge in the disassembly, I thought the second piece followed rather easily.
It is at this point that you can use a rotational move to easily remove the third piece, and for a while I was at a loss for the 'real' way to do it. Eventually I figured it out, but it took me a while to discover it. Once you have the third piece out, the rest comes apart quite easily.
I kept pretty good track of the pieces as I was taking it apart, since it was sure to be a real pain to put back together if the pieces got scrambled. Fortunately this enabled me to put it back together fairly quickly. Considering the amount of time I spent with it, I think even if I jumbled up the pieces I would remember what colors went where, which is the downside to having the pieces be multi-colored (though it looks nice!)
The solution sequence for this burr is 37 steps long, with the beginning being the most interesting and difficult part. There are plenty of dead ends that make it a challenging and interesting puzzle. It really makes you think about how the pieces interact in order to find the solution. It could take quite a while if you are just fiddling with it idly, since it would be pretty difficult to identify the correct path by chance.
The solution booklet is pretty clever: you can read through it from front to back to disassemble it, then you can turn it over and read it backwards to re-assemble it. I didn't try to follow it through the whole way, but they seem quite clearly written in case you get stuck.
Another nice feature is that the pieces have little marks on them so you can gauge how far you are moving the pieces. This is quite helpful for lining the pieces up, since it would be hard to tell otherwise.
I think the only downside to the puzzle for me is that one rotational move. It was almost a challenge to keep the pieces from rotating while I tried to find the correct solution: once I got two pieces out there was plenty of room for rotations. Still, this is not a big issue because the most interesting part of the puzzle comes at the beginning.
Overall, Zig Zag Knot is another great puzzle by ThinkFun! I am always happy to see interesting and challenging puzzles like this reach a wider market.
19 hours ago