Denksport, a cleverly designed puzzle by Jean Claude Constantin for the sport enthusiasts. With multiple solutions, it will keep you entertained for a while. You won't be exercising your body, but instead your brain.

Denksport has a different twist on the 2D puzzle principle, where instead of just randomly placing polyominoes on a frame, you'll need to think ahead and strategize how each pieces is used. With eight pieces and a 6x6 frame, there will still be six empty units around the frame. With those empty spaces, you have to come up with a solution where after placing all the pieces, only identical images are shown. It's more difficult than it looks, but a very interesting concept nonetheless.

At the bottom of the frame, different images related to sports are shown scattered around. Each type of image has duplicates at different positions, so when you decide which image you're going for, the pieces have to cover all other images and leave six identical images. There are six different solutions, one for each sport represented.

This puzzle can be really challenging, since the area you can use for the pieces is always invisible and you have to picture it in your mind. You might want to actually draw the grid in a piece of paper and black out the squares that belong to the images you selected. That way you'll be able to work out better the solution.

Closing Comments:

Denksport is a really nice puzzle with multiple solutions. Although challenging, it remains fun since there are many ways to do it. It makes for a great gift for the sports fan.

Availability: Denksport is available at PuzzleMaster for $26.99 CAD. You can also browse many other interesting puzzles by Constantin.

I've reviewed so many puzzles by Jean Claude Constantin over the years that I ran out of adjectives to classify his unique designs. Probably one of the most prolific puzzle designers/manufacturers in recent history, each puzzle you try from him is bound to leave a positive impression on you. So, what to say about today's featured puzzle, Ella Propella? To put it simply, yet another impressive design.

Ella Propella - That's a pretty nice name right off the bat. And the design is something that catches your attention right away. Including a propeller, magnets and a metal sphere. What else to make this a very unique and interesting puzzle... You're gonna need some dexterity, a good amount of trial and error, but in return you'll get a high dose of fun.

The puzzle may seem confusing at first, as the movement is somewhat stuck by a pin that keeps the propeller moving. You can see what's going on below through the acrylic disc, but you have to figure out a way to make the pin drop and rotate the propeller so that the opening for the sphere can be seen. This movement is a bit of a hit or miss, because the two magnets below repel the natural movement of the puzzle. So you have to keep trying until the pin finally drops and the propeller is free.

Another good thing about the puzzle is that it has a high replay value, since you can't always solve the puzzle at your first try (you probably never solve it at your first try), so it's kind of a fun puzzle to keep around and play to release your stress. As far as difficulty goes, the level 7 is an appropriate classification, as it's challenging but not overly complex that would drive away casual puzzlers.

Closing Comments:

Ella Propella is a really nice little puzzle (just 7.5cm or 3" in diameter), and it's an intriguing puzzle that will keep many occupied for hours. Puzzles and magnets always make for a nice combo, and this time is no different. A definite worthy choice for your collection or just to have a good time.

Availability: Ella Propella is available at PuzzleMaster for just $23.99 CAD. Check out the large collection of Constantin's puzzles also available to purchase.

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Mazes have intrigued and fascinated us since the dawn of civilization. In fact, the Egyptians are thought to be the first ones to come up with this incredible concept over four millennia ago (around the time of the first ancient pyramids). Mazes have come a long way since the era of the Pharaohs. They have evolved in countless different ways and have many different uses, but the approach is the same: to baffle and perplex anyone that witnesses this incredible feat of human inventiveness and ingenuity.

Many people use the terms Maze and Labyrinth interchangeably, and that's probably correct in most cases. However, personally, I prefer to use the word Maze when referring to puzzles. Why? Because a maze always has dead ends and other red herrings, commonly used in puzzles, and a labyrinth is not always used as puzzle, which implies a solving process with a beginning and an end.

Today you can see mazes everywhere in your daily life, but I want to focus particularly on the mechanical maze puzzles, the ones that you can touch and play with, the ones that make me glad I'm a puzzle enthusiast, collector, solver...and writer... There's an array of different types of mazes that can please even the most uninterested of puzzle fans. They can go from simple ball-bearing puzzles, like the popular money puzzles, for the casual puzzler, to more complex structures, like the Perplexus puzzles. Whichever type of puzzle you choose, a maze always has the ability to entertain and satisfy our needs for a good mental challenge.

With so many types of mazes available, how do you choose the best ones? It all depends on what you like most about maze puzzles. One popular type of maze, usually used as an original gift, is the money mazes. This type of puzzles have a wide range of shapes and sizes. The goal is to navigate a ball bearing through a maze and unlock the mechanism that opens the puzzle so you can retrieve what's inside. You can put inside the puzzle anything not thicker than a few sheets of paper, which can be money, gift certificates, event tickets, etc.

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Double mazes are also fascinating in the sense that you have to keep in mind your progress on both of them simultaneously. There are many good examples, and Jean Claude Constantin is a craftsman that knows very well how to make a good maze puzzle, especially when two, or more, mazes are involved. His puzzles have a great complexity, and are mostly appreciated among expert puzzle enthusiasts for their unique designs and mechanisms.

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Final Thoughts:

Mazes have evolved so much over the centuries that it's unfathomable to even think of how they will continue to baffle us in the coming decades. Judging by what history taught us time and time again with new inventions, it's safe to say that mazes are here to stay for as long as civilization exists. It's part of we are, part of our curious minds, and it's essential to our development as an intellectual species. I sincerely hope that, after reading this, you'll be more inclined to try a maze puzzle - any maze - and see for yourself how fascinating these puzzles can really be.

Availability: Most of the puzzles above mentioned are available at PuzzleMaster.

Jean Claude Constantin makes great maze puzzles and proof of that is in some of his earlier creations, like the Two Keys, the Blumenlaby, the Scheibenlaby or even the Labynary. Each one has its own unique characteristics which make them a joy to play with. The Labylong is another interesting design, made as a double-layer maze - Double the fun.

The Labylong is made from laser-cut wood and acrylic. Even though these are cheap materials, the puzzle itself is well built and feels sturdy. Measuring 10.4cm x 6.5cm (4.1" x 2.6"), the puzzle is small enough to carry along with you anywhere, and easy enough so that anyone can try it.

In this puzzle, a small metal sphere moves inside the two mazes, navigating through small holes that connect both mazes. Not all paths will lead to the exit, but that's expected in a good maze. Before making the sphere advance you should study the path ahead and see where it leads. Starting from the exit to the current position will help to avoid dead ends. To navigate the sphere you need to tilt the puzzle back and forth, since the mazes are stationary, and sometimes you need some dexterity to get the sphere where you want it.

Difficulty-wise, I was expecting a tougher challenge, since this is rated as a level 8/10, but I was able to solve it in just a few minutes. Or maybe I'm getting better at maze puzzles... If you've solved one of these, let me know how long it took you.

Closing Comments:

The Labylong is a nice puzzle that even casual puzzlers will like it. If you found it too easy, try to solve it in a different orientation from the one you solved it, or try to go from the exit to the start. It's a fun puzzle to play with, but don't expect a difficult challenge here. Remember, not every puzzle needs to be difficult to be fun.

Availability: The Labylong is available at PuzzleMaster for $18.99CAD. Many more interesting puzzles from Constantin are waiting for you here.

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Made with laser-cut wood, C'est la Vie! is quite a big puzzle, measuring about 13cm in diameter. The designer not only created a challenging labyrinth to navigate, but also a beautiful pattern with curved shapes. Across the entire puzzle you see many indentations in the walls of the pattern, which serve as gateways for the metal ring to go from one section to another. Not all walls have one of these gateways, so you have to plan your moves strategically.

Curiously, this puzzle reminds of the popular Cast Plate by Nob Yoshigahara. Hanayama's version is a lot smaller, but the goal is quite similar, as you try to free a ring from a metal plate. Both puzzles are rather difficult, so I recommend any of them if you like a good challenge.

As you start to solve the puzzle you see the ring in its starting position at the center of the puzzle (Indicated by the letter S). The exit point is located at the left edge of the puzzle, but to get there you'll need to wander for a while, because the path is not a straight line. To get from one point to another you have to be constantly rotating the ring back and forth. Some points will feel a bit tight, as if it wasn't possible to go through there, but if you insist with a slight push the ring will surely pass through. Don't use excessive force, though, because the wood used in this puzzle is fragile and you could end up breaking the puzzle.

This is quite a difficult puzzle to solve. As an experienced puzzler, it took me over half an hour to solve it for the first time. Returning the ring to the starting position is probably a little easier, but still challenging.

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C'est la Vie! by Constantin is indeed a great puzzle and a must-have in any collection. It has a complex shape, but it's very easy to understand, so even a beginner can try to solve it. With a big size and a beautiful design this will sure capture anyone's attention wherever you take it.

Availability: The C'est la Vie! puzzle is available at PuzzleMaster for $31.99 CAD. Check out other puzzles by Constantin.

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This puzzle is quite big, measuring about 13.5cm in diameter, and it's made using laser-cut wood and acrylic. This is also a rather intriguing puzzle because of how its mechanism works. Between the two layers of the labyrinth there's an acrylic disc with three holes in it. These holes are placed at different distances from the disc's center, making it easier to go from one place of the labyrinth to another just by rotating the disc.

Starting from the entry hole, your goal is to guide a metal sphere through the double labyrinth until you can reach the exit hole on the opposite side of the frame. The name of the puzzle is very fitting, since its name in German means "Sliced Labyrinth". As you navigate around the maze, you'll find that each section is very short, and the only way to proceed is to rotate the disc and get the sphere through one of its holes and into another "slice" of the maze. You have to go though both mazes in order to successfully solve this puzzle.

Finding the exit is a little difficult, but I was able to solve it within five minutes. There are a few dead-ends here and there, but overall I think the difficulty is about 8/10. Some of you may spend some time going backwards or even returning to the beginning by accident - it happened to me as well - but it's not a frustrating exercise and you'll eventually find the exit if you insist and have a little determination.

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I really liked the Scheibenlaby. Constantin always finds new ways to build original and unique puzzles that give you lots of fun and are a pleasure to play. You don't need to be an experienced puzzler to enjoy this one.

Availability: You can find the Scheibenlaby puzzle at PuzzleMaster for $41.99 CAD. Check out other puzzle by Jean Claude Constantin.

The Bike Shed Puzzle is the second of four different Picture Frame puzzles made by Jean Claude Constantin and distributed by Recent Toys.

In this Transport Arrangements series, each with a different theme, Constantin chose four transportation vehicles, and this time, it's an eco-friendly one, the bike. Five different bike models have to be arranged within the frame, which itself has the shape of a vintage bike model. The pieces have to be arranged in a way so that they can hardly move, but not overlapping and outside the frame boarders.

This type of puzzle is a little different from the usual packing puzzle, where the pieces have straight lines and geometric shapes. In a Picture Frame puzzle, however, the pieces are irregular and the thinking process is different, where you need to see how the empty spaces can be used.

For a typical Picture Frame puzzle, the Bike Shed is quite challenging. There are lots of circular shapes to maneuver around the frame, which makes it quite difficult to do in a small area. It's a level 8/10 puzzle and I believe it's an accurate rating.

Closing Comments:

Picture Frame puzzles are quite fun to do, since the pieces are not abstract, like squares or other geometric shapes. You can actually feel the shape of the bikes in your hands and the overall experience is much more fulfilling than a regular packing puzzle.

Availability: You can find the Bike Shed Puzzle at PuzzleMaster. All four puzzles of this series are also available.

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The name Zauberseil means "Cotton Rope" in German - it's a rather fitting name, since the rope used here is made of cotton. As you can see, the rope is also much thicker than the usual string puzzles and less malleable, so it's a little harder to maneuver it. It's also shorter than other puzzles, but here it could be considered a good thing, because it's more difficult to create undesired knots. The frame is made of thick metal, so even if you apply some force it won't easily bend and deform the puzzle.

The Zauberseil is made of three metal parts, a large ring and two identical U-shaped pieces. These pieces are entangled together with the rope to form a devilishly difficult puzzle that will surely put your skills to the test. I believe only the rope can be freed from the puzzle, but it's possible that one of the U-shaped pieces could be removed as well.

The puzzle is, in my opinion, at least a difficulty level 9/10. I couldn't solve it yet, so I believe it's as difficult as they come. Judging by the nature and design of the puzzle, I suspect that the solution is only a couple of steps, but they surely are very well hidden under the apparent simplicity of it. If you like a good and near impossible challenge, then this is a perfect puzzle for you.

Closing Comments:

The Zauberseil by Jean Claude Constantin is not a puzzle for everybody. It can become extremely frustrating to solve if you don't have any previous experience with this type of puzzles. However, if you feel courageous enough, then solving it will provide a truly rewarding experience.

Availability: You can find the Zauberseil at PuzzleMaster for just $10.99 CAD. For more Constantin puzzles, click here.

It's been a while since I reviewed a Framed Picture Puzzle. I always loved these, though. It's a packing puzzle, but the pieces don't get to be all neatly packed with straight angles. Since there are empty spaces in between, you also need to carefully plan where every piece should go.

Jean Claude Constantin has a new series with Transport Arrangements as the main theme, with four puzzles like this, all distributed by Recent Toys. Each puzzle has its own theme and the one featured in this review is all about vessels you can dock at a harbour. The Harbour Puzzle has nine pieces, each with a different shape and color.

One negative side about this puzzle is that it comes in its solved state, which I completely disagree. What were they thinking? The moment you see the puzzle, you can't avoid not seeing it completed, which will surely affect the way you solve it later, since you will probably remember how some pieces were packed. You can ask someone to unpack it for you, though, which I highly recommend.

The puzzle itself, however, is well built and despite being made from laser-cut wood, its quality is really good. The different wood colors give it a sophisticated look and elegance you can't get from using the same wood color. Compared to other Picture Frame Puzzles I have, the size is on the small side, but still quite enjoyable to play with.

As for difficulty, it's exactly how you would expect it with a puzzle of this type - quite challenging. You can't avoid being at the mercy of trial and error, but not as much as a convencional packing puzzle, since you do need to carefully think how each piece can be packed without wasting too much space inside the frame. The frame itself is irregular which will make it even more difficult.

Closing Comments:

Solving these puzzles is a quite enjoyable and rewarding. The replay value is low, since there's usually only one solution, but for less than $20, you get quite good value for your money, because it's still a rather challenging puzzle. There are four different puzzles in this series.

Availability: You can find the new Constantin puzzles and The Harbour Puzzle at PuzzleMaster for just $17.99 CAD. Check out dozens of other interesting puzzles from the German designer.

Jean Claude Constantin has spoiled us over the years with his creations, with high quality puzzles and beautiful designs. As if all this wasn't already good enough, it seems this time he outdid himself. His new line of puzzles goes a step further in the quality department and the result pops out right in front of your eyes.

The Slide Elox is one of three puzzles currently being made with anodized metal. The other being the Nur 8 and the Farbenspiel 6x6. This material in contrast with the black frame makes an exquisite and unmatched striking colorful effect. Acrylic is also used for the sliding pieces, creating a perfect harmony with the metal and the laser-cut wood. The movement of the pieces is quite smooth against the wooden frame, providing a rather satisfying experience.

There are 16 small cylinders neatly placed around the perimeter of the frame, while inside, eight acrylic pieces have to be arranged so that the larger cylinders match with the same colors on the frame. With only a small gap in the frame to slide the pieces around, this will prove to be quite a challenge.

Speaking of a challenge. There are actually eight of them for you to solve. Each challenge has a different starting position, meaning more moves as the level of difficulty increases, but they all share the same solution. This has been such an incredibly difficult puzzle that I only managed to solve one out of eight so far. I solved the level 2, while the level 1 has me stumped with only the two small squares being in a parity problem, where their positions are opposite one another.

Not surprisingly, this is rated as a difficulty level 9/10, as this is not your average sliding puzzle. One of the reasons is that the pieces have different orientations, where some move horizontally and others move vertically. The two small squares move more freely, but they still have their limitations when moving around the frame. It's truly a great challenge.

Closing Comments:

I'm a big fan of sliding puzzles. And when you combine one of my favorite puzzle designers and a beautiful, close to perfect, presentation it all clicks together in a one of a kind puzzle. The Slide Elox is now one of my favorite Constantin puzzles.

Availability: The Slide Elox is available from PuzzleMaster for $54.99 CAD. Check out also other great puzzles by Constantin.

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There's one thing that I like more about wire-only puzzles than the string ones - You can't make knots out of the wire puzzles, and thus it's much more unlikely to get stuck in the middle of the solving process. There are ways to get stuck anyway, but you have to be very creative to accomplish that.

The Euro puzzle is made from thick wire (3mm) and measures only 8.7cm in diameter. The design is made to resemble the shape of the Euro currency symbol, and the goal is to remove the ring (or to separate all three parts). The ring seems to be trapped between the two main parts, but a clever series of movements will be enough to solve it. Finding these moves, however, will be a bit tricky.

This puzzle reminds me of the classic Horseshoe puzzle, where you also have a ring trapped between two metal parts. The Horseshoe is much harder to solve for a beginner, but the solution is a bit different in the Euro puzzle. The two main parts are attached in a similar way as a hinge works. You can easily unfold the puzzle in 180º, but after that there's not much else to do. The key lies in the hinges, so my advice is to keep trying until you finally solve it.

It took me much more time to put the puzzle together in its original form than to take it apart. Figuring out how the puzzle works is the key to understand its mechanism, and until you do you won't be able to fully solve it.

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The Euro is a great puzzle that really gets you thinking in ways that you're not usually used to. I like that its all metal and no strings, so it's less frustrating to solve. You can lend it to a beginner and have no problems afterwards without knots for you to untie.

Availability: You can find a copy of the Euro puzzle at PuzzleMaster. As usual, Constantin has a lot of interesting puzzles, so be sure to check them out as well.

If packing puzzles weren't already difficult to solve, Jean Claude Constantin makes them even more challenging by always adding a twist. After all, we like challenging puzzles, don't we? My recent addition to this ever-growing collection of difficult puzzles is called Nimm 2. The name indicates that there may be a first Nimm, but in reality Nimm in German means "take", so the name can be translated as "Take 2". Read more and you'll understand the meaning.

This is a nice small puzzle, measuring only 8cm x 8cm (3.2"). It is made from laser-cut wood, so the price is more affordable. There are 7 pieces, but they can be divided by two groups: one is a group of three trominos and the other a group of four tetrominos. Each piece has one or two screws attached to it, which makes for an interesting design. The idea is to have two screws in every row (vertical and horizontal). Diagonals don't count. It sounds simple enough, but believe me, this is a fiendish one to solve.

Solving the puzzle without worrying about the screws is very easy. That's why the designer wanted to make it as simple as possible. However, packing the pieces with the one rule mentioned above is more than just a simple exercise. It requires patience, and much trial and error. But that's what most packing puzzles require, so it's asking you anything new. If you're used to solving this kind of puzzles you know how to go about solving them, at least in principle...

As you can imagine, this is quite a difficult puzzle to solve. It's rated as a level 8/10, but I reckon it's possibly even more than that. I'm yet to find the solution, which might be a unique configuration, and thus explaining why it's so challenging.

Closing Comments:

Nimm 2 by Constantin is a hell of a challenge. If you like this type of puzzles, you're in for a treat, because it'll keep you busy for a while. I liked the originality of the design. It's different from any packing puzzle I've tried before.

Availability: The Nimm 2 puzzle is available at PuzzleMaster for $23.99 CAD. You can also check out other cool puzzles by the prolific puzzle designer Jean Claude Constantin.

Which company/craftsman makes the most beautiful puzzles?

- In my endless pursuit to answer this question, this time I will focus on one of today's most prolific puzzle designers out there - and my favorite - Jean Claude Constantin. The name suggests a French origin, but Constantin is, in fact, from Nuremberg, Germany, where he produces in his shop over 70 new designs each year; and having been a puzzle designer for so long, imagine the total number of different puzzles he's been able to make so far. I currently own about 100 of his puzzles, so I can only dream of having, one day, all of his puzzles...and at the current rate he's making them, it's an almost impossible feat.

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Anyone that's familiar with Constantin's puzzles knows what characterizes them, what makes them so appealing to puzzlers and collectors alike. Any seasoned puzzler can spot a Constantin puzzle quite easily, as his designs always feature something new and clever in their concept. Their presentation is very well thought-out and elegant, and despite his materials often not being top-notch (laser-cut plywood), you can always count on a high quality finished product at a very reasonable price.

Another impressive aspect about Constantin's puzzles is the diversity of designs available. Today, the majority of puzzle designers only dare to make one type of puzzle, and will perfect that craft over the years - That's the rule.  However, Jean Claude Constantin is the exception. He can basically make any type of puzzle, from 2D/3D packing/assembly puzzles to sequential movement, wire/string, interlocking, puzzle boxes...you name it. And yet, each puzzle will be superbly made as if it were his first-ever design, having its own personality and special features. No matter what your collection focuses on, one thing is certain: Constantin has at least one puzzle that satisfies all your requirements.

While most of Constantin's designs are made using plywood, he also has pretty interesting puzzles made from natural wood, like the Skyline, or the Eingeengt, or the Metalwurfel, or the Brochettes, just to name a few... As you can expect, these puzzles tend to be more expensive, but considering the materials used and their level of detail, they're still quite cheaper than many other renowned craftsmen's.

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Whether it's natural wood, or simply plywood, another important trait in Constantin's designs is the use of many different wood shades, sometimes combined with other materials such as metal. Since the colors are all natural and not painted, it results in a more beautiful and exquisite effect for all his puzzles. An example of this, seen in this rather simple design, the 1 x 9, nine different wood colors are being used for the pieces plus another one for the frame. Two other gorgeous puzzles that make good use of this design philosophy are the Jahresringe and the Pentag Zigzag, both made from eight different wood colors (pieces plus frame). Even when a puzzle consists of just two wood tones, he chooses two highly contrasting colors for maximum effect, like the Tetris puzzle (seen below).

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Packing Puzzles are one of my favorite type of puzzles, and Constantin provides me with way more designs than I can handle, so it's always a difficult task having to choose a couple of them whenever I want to place a new order at a puzzle store. Having been collecting puzzles for over six years now doesn't give me the time (or money) necessary to own every single packing puzzle he makes, but I believe the ones I already have are sufficient to have, at least, scratched the surface.

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If Packing Puzzles are not your thing, not to worry... Constantin has something for everybody, and one of the most popular type of puzzles lately proves just that. I'm talking about n-ary puzzles, of course, the favorite subject of experienced puzzlers that demand harder challenges and beautiful designs to go with it. N-ary puzzles are sequential movement puzzles that require a recursive solution.

The first n-ary puzzle was the Chinese Rings, invented in the 10th century. Because the solution is interpreted as having only two states (0 or 1), it's called a binary puzzle. Over the years, puzzles have evolved to ever more complex designs and today you can see ternary, quaternary, quinary...up to 15-ary (or quindenary) - this n-ary record holder belongs to Jean Claude Constantin's Generation Lock with a whopping 340,000,000+ moves. You'd need a few extra lifetimes to solve this one...

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Constantin is also an authority on puzzle boxes (also known as trick boxes), another soft spot of my collection and the subject of a few personal favorites. His designs are a bit different from the traditional Japanese Puzzle Boxes, but that doesn't mean they're not as impressive. Usually, his puzzle boxes are very well decorated and unlike their older cousins, only a couple of moves are necessary to open them. Mind you, a couple of very-difficult-to-figure-out moves. These boxes are considered as perfect gifts for puzzle enthusiasts, since you can always hide a surprise inside (money, jewelry, or other similarly sized objects) for when that person opens the box.

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Last, but not least, Trick Locks... This is yet another fascinating type of puzzles that has a wide variety of designs and concepts, and there are people that devote entire collections exclusively for these puzzles. As expected, Constantin has a very important role on the design of some of the most impressive trick locks out there. Trick locks can have between two to hundreds of steps necessary to unlock them. Some have hidden mechanisms, where you need to use other senses besides your vision; most of them don't even need a key in order to be opened, while others need a more patient solver, since there are some locks that make a clever use of the n-ary concept, and Constantin seems to be an expert in this field.

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Whether you're a veteran puzzler or you're just venturing into this fantastic hobby, having a few Constantin puzzles will go a long way to enrich your collection. After seeing so many beautiful designs by this talented puzzle designer, I can truly say that there's nothing he can't do when it comes to wooden puzzles. What's mind-boggling is that he doesn't seem to be running out of ideas anytime soon, and for that I can hardly wait to see the next 70 or so new designs he has in store for us next year.

Availability: You can find many of Constantin's puzzles at PuzzleMaster.

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Imagine, a padlock without a key. That would be great, because you could open it without worrying about losing its key. But, there's a downside with this puzzle lock. To solve it, you'll need at least 250 steps - hence the name of the puzzle - which can take a while to open it. However, it's a perfect way to keep something of value locked, since it would discourage any thief from attempting to rob you, lest they would get caught with the hands in the cookie jar.

The Schloss 250 has a robust body made of laser-cut wood. Four pins are held in place in the middle and stuck between the four wooden plates that cross the lock from one side to the other. The pins can only be moved from left to right, but you have to unlock their path with the correct sequence. The movement of the puzzle could be better, because it can be stuck sometimes and you risk losing your concentration. Other than that, it's very well made.

The solution is simple, but at the same time, complex. This seems quite an incoherent thought, but it's actually true. The solving process implies the use of recursive mathematics, which means it has a specific set of rules that will repeat after a while. While it can be complex due to the number of moves needed to solve it, and also extreme concentration, once you understand the repetitive nature of the solution, it becomes very simple. This is a puzzle belonging to the group of 6-ary (remember that binary has only two states, 1 or 0), which means it has six different states. Understanding this notion will help you a lot in solving this challenging puzzle.

Closing Comments:

The Schloss 250 by Constantin is a true test to anyone's patience. With its whopping 250 steps, although it can take you more, only the most courageous will succeed in solving this fiendish puzzle.

Availability: PuzzleMaster is the place to get this great puzzle. If you want a less challenging puzzle or any other from Constantin, you can browse his available puzzles.

If packing puzzles weren't difficult already, there's another type of puzzles that promise to elevate the difficulty to much higher levels. These are called constrained packing puzzles and, like the name suggests, you are constrained by a limited number of moves as you try to pack the pieces inside the frame in a specific order. Eingeengt 2 is one for the courageous puzzle solver...

Eingeengt 2 was designed by Jean Claude Constantin and, as you might've guessed by now, this is the second design of this type. You can check out my review for that one from six years ago. Back then, I loved the idea and concept of the constrained puzzle, and this time it's no different. It's a really clever design, which defines what a great challenge should be.

The new design features seven pieces, one more than its predecessor, and a different way to constrain the pieces. The acrylic cover of the frame has a shape cut that only lets one piece at a time to be fitted, and even then, you must slide the already fitted pieces around so that it allows for the remaining pieces to be placed. The solution is sequential, and only a careful planned strategy will solve it.

The puzzle is rated as a level 8/10, like its predecessor, but to my experience this one is much more difficult to solve. It's at least a level 9/10, in my opinion. It has a higher number of moves and the one extra piece is enough to exponentially raise the overall difficulty.

Closing Comments:

Despite it's higher difficulty, Eingeengt 2 is a superb puzzle. It's not like many other packing puzzles where the solver attempts to solve it at random. There's a logic solution behind it that must be discovered, and that makes the puzzles quite fascinating. A must for experienced puzzlers.

Availability: Eigeengt 2 is available at PuzzleMaster for $18.99 CAD. Many other interesting puzzles from Constantin are available.