The Concentric Arc is a maze puzzle.  On both discs  there are curved channels cut out. These form 3 layers of “concentric circles” spanning out from the centre. The puzzle is made of trespa, a strong and durable material widely used for home table surfaces. The puzzle is precision laser cut and the quality of construction and finish is very good.

To solve, one needs to rotate the two discs (held together at the centre by screw) and navigate a rivet “floating” along the maze channels to a point where it can be fully removed. And to remove the rivet, the round hole on the top disc must coincide with a similar hole on the bottom disc.

OH NO!, another maze puzzle which i can’t solve?

When I first looked at the Concentric Arc, it reminded me of the Cross & Crown, Dr Goetz Schwandtner’s IPP34 Exchange Puzzle. This is another maze puzzle with two similar looking discs having all the cut-outs and such. However the latter is a N’ary style puzzle, requiring a lot more moves in a particular sequential fashion. Moreover I was not able to solve the Cross & Crown successfully either.

Nonetheless as I fiddled with the Concentric Arc, I found it to be less intimidating than I initially thought. In fact, after several minutes of play, I managed to remove the rivet. But to really solve a puzzle fully, you must be able to return the puzzle to the original state, at least one senior seasoned puzzler has exclaimed. Here is where I had a tad more problem than before. I had forgotten the moves. So I thought again with my random fiddling, I would be able to get the rivet back in place somehow. But this was not to be for quite a while, in fact quite a long while.

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I first saw the Mobius at the Singapore Puzzle Party in 2015, where Oskar was on a business trip to Singapore.  A bunch of us puzzle enthusiasts met him for a nice puzzle evening over dinner. There, he showcased an array of twisty puzzles (a number of them new prototypes) and also brought along a Cast Mobius (prototype?). I didn’t get a chance to try the Mobius that night. Finally at IPP37 in Paris this past August, I snapped up one during the Puzzle Party.

The Mobius is based on the Mobius Strip. The object of the puzzle is to remove the round disk from the curving “strip” which has protruding bumps and forms a maze along both surfaces. Without “entering” the maze, the disk can actually travel along the curves of the strip and the orientation of the disk as it travels the entire length changes. The strip is made of zinc alloy and the disk aluminium. Talking about the Mobius strip, Japanese designer Hirokazu Iwasawa also designed the Zipper using the same concept.

The Mobius measures about 6.5cm x 6cm. Quality of construction is up to the usual Hanayama standards. The puzzle itself is not hard but will still provide a fair challenge for novices. It is rated 3 stars by Hanayama and that level of difficulty I think is about right. Perhaps maybe even 2.5 stars. Still a bit tricky somewhat and not as straight forward as one would expect. It took me a couple of minutes and I had the disk out in no time. Putting the disk back was just the reverse. One of those puzzles where persistence would eventually get you to the solved state.

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