Napoleon and the Policemen

Napoleon has landed on a deserted planet with only two policemen on it. He is traveling around the planet, painting a red line as he goes. When Napoleon creates a loop with red paint, the smaller of the two encompassed areas is claimed by him. The policemen are trying to restrict the land Napoleon claims as much as possible. If they encounter him, they arrest him and take him away. Can you prove that the police have a strategy to stop Napoleon from claiming more than 25% of the planet’s surface?

We assume that Napoleon and the police are moving at the same speed, making decisions in real time, and fully aware of everyone’s locations.

First, we choose an axis, so that Napoleon and the two policemen lie on a single parallel. Then, the strategy of the two policemen is to move with the same speed as Napoleon, keeping identical latitudes as his at all times, and squeezing him along the parallel between them.

In order to claim 25% of the planet’s surface, Napoleon must travel at least 90°+90°=180° in total along the magnitudes. Therefore, during this time the policemen would travel 180° along the magnitudes each and catch him.

Sunome Puzzles


Sunome is a new logic puzzle, invented by Adam Bontrager. The name is an abbreviation of “Suji no meiro” which means “digit maze” in Japanese.

Sunome puzzles come in the form of a grid with numbers on the sides, and a Start (S) and End (E) cells inside. The goal is to design a “proper” maze with the given Start and End cells, such that the amount of vertical and horizontal walls in each row and column is predetermined by the numbers around the grid. The meaning of “proper” involves a lot of technical requirements, such as existence of a unique path from Start to End, lack of closed off regions, etc.

Initially, the rules of Sunome seem relatively complex in comparison to the likes of Sudoku and Kakuro. However, it takes little time to get a good grasp of them. The clues regarding the number of walls in the rows and columns are the ones used mostly, just like in a Nonogram. Once the player gets stuck, they need to apply some of the other rules, which unlock the solving process further. Overall, I find the experience highly enjoyable, since it requires paying attention to multiple components at once.

Each puzzle in the Sunome books is manually designed, so that the solution can be deduced analytically, without the need of a trial-and-error approach. The difficulty is generally lower than Sudoku and Kakuro which allows the player to complete a few puzzles in a 10 to 20 minutes long break and get back to working on other things.

While the original Sunome puzzles would hardly get boring, the author makes sure new puzzle mechanics are introduced in each successive book in the series:

  • BOOK 2: Pits, Portals, and Passages – adds objects and complexity to the grid
  • BOOK 3: Sunome Cubed – changes the shape of the grid to a cube
  • BOOK 4: Sunome Blocks – instead of a creating a maze, the player must break the grid into shapes with predetermined sizes, similarly to Shikaku
Sunome: Pits, Portals, and Passages
Sunome: Cubed
Sunome: Blocks

In addition to Sunome, the author has started publishing a separate series of original Transportation puzzles. So far this includes Kartdoodle and Skyways, with Railways coming out soon. While all puzzles are highly entertaining, my personal favorite so far is Skyways. It plays a lot like Numberlink and the mobile game “Flow Free” but has some added complexity.


One can get the PDF versions of the books from for merely $1 each (at the time of publishing this post), which is a great bargain for such a good bundle of puzzles. Physical versions are also available on Amazon for $8. Each one of them is in the form of a small-format softcover, ideal to keep in the bag during travels. I hope the author will eventually consider combining all Sunome books in one deluxe hardcover edition and will do the same with his Transportation puzzles.

If you are still not convinced about Adam’s original puzzles, you can try the free sampler provided below. Also, for just a few bucks per month, you can subscribe to his Patreon. I am very happy to see such a prolific puzzle creator and looking forward to try his future work.

  • about 100 puzzles in each book
  • all hand-made logic puzzles
  • variations keep the puzzles engaging
  • affordable PDF and physical formats


Out of Time

In the position below, Black played a move, but right before he pressed the clock, he ran out of time. However, the judge declared a draw instead of awarding a victory to the opponent. Why?

The rules of FIDE state that if a player runs out of time, their opponent wins the game IF they have a path to victory. If there is no sufficient material, e.g. a King and a Knight against a King, then the game is declared a draw.

In this position, Black played Rxg6 which forces the moves:

  1. … Rxg6+
  2. Nxg6+ Rxg6+
  3. Kxg6+ Qxg6+
  4. Kxg6

This leaves White with a King and a Knight against Black’s King. Thus, White did not have a path to victory and the game was declared a draw.

Journal 29


“Journal 29” is a series of three interactive book games by Dimitris Chassapakis, which were consequently re-released together in one premium hardcover edition. Each of the three books contains about 100 pages, full of creative puzzles and cryptic imagery. The puzzles are in the spirit of real-life Escape Rooms, mostly visual and loosely connected with an underlying story about alien encounters.

Journal 29 trailer

What made me immediate impression is the effort put into making the book resemble an actual journal. The illustrations look like they are scribbled with a pencil, the pages are yellow and have smudges all over them, the font is handwritten. There are QR codes printed on every other page that give quick access to online solution checkers, and their design fits well the Sci-Fi/mystery theme of the book.

In order to navigate the journal, the reader needs to use the official website, so internet access is required. Each puzzle has its own unique URL, where the reader can input their guesses. If a correct answer is given, a KEY is provided which can be used for solving further puzzles. Currently, the keys need to be written down and stored manually. A nice potential feature would be if users could create accounts on the Journal29 website and have their keys stored there automatically.

While I appreciate the high quality art, the most important components of the book are naturally the puzzles. There is a great variety of them, providing a mix of both old and new ideas. The reader will encounter various cyphers, optical illusions, and classic puzzles with unique twists. In addition, a large assortment of new creative puzzles is devised.

As of writing this post, I have just finished the first book in the series. I find the puzzles so far to be very well-designed and logical, with varying levels of difficulty. Some ideas were naturally familiar to me, but there were also a lot of new, unexpected “A-Ha” moments. I particularly loved the way some of the puzzles required me to explore the book and interact with it in clever ways, like solving a mechanical puzzle.

My only criticism is that on 1 or 2 occasions I had to use Google search. Of course, this is necessary when a message in Braille or Morse code needs to be deciphered. However, I prefer that it is avoided for researching clues that are not considered common knowledge.

Above, three of the puzzles from Journal29 are presented. While many of the puzzles in the book are dependent on each other, these three can be solved separately. You can verify your answers using the official solution checkers provided below each puzzle. If you encounter difficulties, you can take a look at our hints.

This is a message written in Braille.

The code for each sector is formed by 3 pairs of digits. The first digit in each pair designates the number of skeleton parts in the corresponding group. The second digit encodes the type of those skeleton parts.

There are 3 differences between the two pictures. Find them and examine their coordinates in the grid.

Once I put my hands on the hardcover edition of Journal29, it quickly became one of my favorite puzzle books. I get back to it regularly, don’t rush it, and simply enjoy my time with it. I always pay much attention to details and I can see the author Dimitris does as well. In addition to designing 160 clever puzzles, he has also supplemented them with beautiful art, developed an accompanying website, and supports a forum where he personally helps readers. He has even built an Amazon Alexa skill that can provide hints for the puzzles if you ever get stuck. I can only appreciate all of that.

  • 160 creative puzzles that take weeks to solve
  • remarkable artwork and presentation
  • accompanying website with solution checkers and forum
  • the hardcover edition looks and feels premium


The Cipher Solver Series


The Cipher Solver Series is a collection of cipher puzzle books, written by D. H. Bernhardt. Each of the books teaches about various cipher techniques and then provides examples that help the reader master them. So far, there are 3 volumes released, and a fourth one is on its way.

Each book in the series starts with a short history on ciphers. Then, it provides 2 chapters on how to encode and decode specific ciphers, followed by 2 chapters with puzzle-examples. Finally, the books end with hints and solutions.

Volume 1 and 2 focus on the so-called Route and Rail ciphers, while volume 3 introduces us to the Pen and Polybius ciphers. The former are examples of transposition ciphers, those are ciphers in which the symbols are preserved, but their order is scrambled. The latter are examples of substitution ciphers, those are ciphers in which the original symbols are replaced with new ones.

Rail Cipher Example

The following example of a Rail cipher is taken out of the first book in the series. Let’s say the task is to encode the phrase “Beware of the attack from the North”. To do that, we create a rectangular grid and starting from the top left corner, we enter the letters of the phrase in a zigzag manner. We add some “X” letters at the end as padding, if necessary. This results in a route-like structure inside the grid, consisting of alternating diagonal rails.

Then, if we read the letters line by line, top to bottom, we get the encryption:


To decrypt an encoded phrase, we just need to determine the dimensions of the grid and the size of the rails of the route. You can practice your route ciphering skills with the following puzzle from the book:

The transposition ciphers are fun but quite easy to solve, especially the Route ciphers. They all have been chosen with identical grid widths, so the only unknowns there are the route rails sizes. I recommend getting just one of the first two volumes, since the novelty in the second one lies mostly in the introductory chapter.

The two substitution ciphers are harder to solve and require more careful analysis. However, it is worth noting that the decoding procedure works identically for both of them, even though the ciphers use different encryption symbols.

Pig Cipher encoding of “BEWARE OF ATTACK FROM THE NORTH”
Polybus Cipher encoding of “BEWARE OF ATTACK FROM THE NORTH”

Despite the remarks above, I think the books are educational, well-structured, and would be engaging to new cipher enthusiasts. I hope once the author completes his series, he considers combining the content in one larger edition divided into sections based on cipher type, such as transposition and substitution.

  • a great presentation on various ciphers
  • engaging educational chapters in the book introductions
  • the route ciphers could have used various grid widths
  • the substitution ciphers decoding works identically


The Password Game

“The Password Game” is a new web puzzle/game by Neal Agarwal, a Brooklyn-based software developer, popular for various fun projects hosted on his website Neil.Fun.

pon opening the game webpage, you are given the seemingly simple task of creating a password. The password, in order to be strong enough, needs to satisfy a list of conditions. The first few of them are common; there is a minimum length and special characters should be included. However, after complying with every rule on the screen, a new one appears, more complex and bizarre than the previous one. This forces you to constantly make changes to the increasingly lengthy password, while trying to resolve any conflicts that appear.

The Password Game is quite difficult. On our first try, we failed the game after not giving in a timely manner a bug emoji 🐛 to a chicken emoji 🐔 inside our 70+ character password, while simultaneously looking for a YouTube video of the exact runtime of 19 minutes and 34 seconds. Hopefully, you can do better.

If you enjoy “The Password Game”, you can take a look at Neil’s other creations, such as “The Absurd Trolley Problems”, which offers sinister twists on the famous Trolley Problem.

Blaž Urban Gracar

Blaž Urban Gracar is a Slovenian artist. He is a musician (composing music for the theater, producing left-field electronica, playing keyboards in a rock band), writer (publishing poetry, prose and comic books), filmmaker (editing and animating short films), and game designer (mostly creating puzzly solo games). He lives by the sea with his partner, her daughter, two cats, a dog and a turtle.


Q. Hello, Blaž!

A. Hi, Puzzle Prime! Thanks for featuring me.

Q. I know you are quite a busy person, I’m glad to have you here.

A. Never too busy to talk with friends! But yes, my calendar has become quite crammed lately. I spend most of my days making music, which is basically my main source of income. I compose music for films and theater, but I also make strange electronic music and play keyboards in a rock band. Besides music and game-making, I also write – I have published a few books – and I make videos. Lately this means making animated shorts, but I graduated as a film editor, so I have made or collaborated on several films.

Q. Sounds great! I would first like to focus on your puzzles though, specifically your first published book, LOK. What was the inspiration behind it?

A. When I was making my previous puzzle book, Lineon, which is sadly still unfinished, I started corresponding with Stephen Lavelle, better known as Increpare, who made a bunch of great and acclaimed puzzle games, among them Stephen’s Sausage Roll, which is praised as one of the best puzzle games of all time. I sent him Lineon and he responded with a set of paper puzzles of his own, which were word-search puzzles using the Toki Pona language. Toki Pona is a constructed language that I don’t understand, so solving these puzzles felt very other-worldly. I started thinking how would such word-searches work if they used a completely made up set of words, which would have meaning only inside these puzzles. If we say “Apple” for example, we mean a red and round fruit. What if a word like “Lok” meant that you could erase a letter and that’s it? This idea felt very interesting to me and I quickly prototyped a puzzle which already used a lot of words that are present in the final book. It then took me about a year before I returned to this idea and saw potential for something greater.

Q. How long did it take you to finish LOK and what was the hardest part?

A. It took me a little more than 6 months to make LOK. I thought it would take me maybe 3 months, as I saw LOK as a smaller project at first, something to make in between bigger projects, so I pushed to finish it as soon as possible and made the first draft in about 2 months. I now see this as a smart approach – to rush the first draft – as it then took me 4 more months to perfect everything and make it really shine. I think it’s really important to have everything in place and see it for what it is, even if it’s not finely tuned yet. The last 10% were the hardest, but this was expected. It took me weeks to decide on some miniature details, like the correct font for titles, or the alignment of chapter artworks. Everything needed to match the vision, and it was hard to be certain what is correct in some aspects. But I’m very happy with how it all came together in the end.

Blaž making music

Q. How do you approach making a puzzle?

A. Well, apart from some rare tributes and try-outs of some already established genres, I generally like to make up my own system of rules, within which I then create a bunch of puzzles. I rarely do one-offs. So, when I first start exploring a new system I made up, I just throw things at the wall and see what sticks. These puzzles are usually ugly, random and without any real a-ha moments, but with them, I kind of expose most of what the system is capable of. I then re-do the puzzles that have interesting interactions or ideas, try to make them more elegant, guided and beautiful, but I also retain some of these early puzzles as they were, because they already work quite fine. So, after I internalize all the ins and outs of a system and start working on proper puzzles, my process is usually thinking of an idea that I would like the solver to find out and then kind of build a pathway for them. I try to think like the solver and how they would react to certain insights and deductions. Basically, I want the solver to have fun and to blow his mind every few puzzles, haha.

Q. How does creating puzzles differ from creating in these other fields?

A. Music, films, prose, all of these art forms are kind of direct compared to puzzle-making. They communicate something in a direct way, even if they are metaphorical or dream-like. Puzzles, on the other hand, work on two levels. One is the first impression: how they look at first sight, if they are symmetrical, big or small, if they intimidate or seem easy. The second level is the hidden meaning of a puzzle, its solution and how you get to it. It feels like designing an onion, where you want to put as many surprises into different layers as possible. You also need to be a lot kinder to the consumer of your puzzles compared to other art forms. You have to respect their intelligence and patience, make the system and a puzzle as mechanically sturdy as possible, because ultimately they need to “get” your message. You certainly need to be a lot more pragmatic.

Q. You come from Slovenia. Is there an active puzzle scene in Slovenia and do you hang out with other puzzle designers?

A. There is no puzzle scene in Slovenia that I know of. It’s strange, because ever since I got serious about game design, I feel like I create in a bubble. When I make music, people around me respond to it, they come to concerts, they buy CDs. Even my books, which are a bit more niche, find some audience in Slovenia. But my games or puzzles don’t really connect with anyone around me. It’s like I live a double life, one with friends and family, and the other just on the computer, which I use to communicate with puzzle lovers from around the world. This is how I got in touch with you as well. When I published LOK, I sold 95% of books to people outside of Slovenia, people I don’t know, people from Europe, America, Asia. It’s strange, but it also feels nice to at least have an audience somewhere, even for my small and weird little games.

Lineon Puzzle Book and Sountrack

Q. What are your next puzzle projects?

A. Based on the response for LOK, I already have many ideas for the continuation of the LOK story. The main one is the digital adaptation of LOK which I’m already working on with Raindrinker, a talented creator from Spain I met online. We hope to publish the game in 2023. Besides LOK, I might return to Lineon and start working on it again from the ground up, with the experience I gained in the meantime. There are some other ideas that I’m bouncing around in my head, maybe also a continuation of my solo card game “All Is Bomb” in some form. Let’s see what happens – I love designing games, so something will probably appear in a short while.

Q. Thanks you Blaž.

A. Thank you, Puzzle Prime!



LOK is a new original puzzle book, created by the musical and visual artist Blaž Gracar. It is his first published work in this domain and considering the attention to detail put into puzzle design, solutions system, and illustrations, I would say that’s an impressive start, and I am looking forward to his future endeavors.

The puzzle mechanics of LOK are quite innovative, and despite my long-time puzzle history, I cannot relate them to anything I have seen before. Each puzzle consists of a grid partially filled with letters and the goal is to black out all cells by marking certain words and then triggering their effects. For example, if one has the letters L, O, K in consecutive cells and marks the resulting word LOK, then they must black out the cells of all three letters plus an additional cell by choice.

There are 5 more trigger words that appear in the book, but since it is the solver’s challenge to figure out what their effects are, I will not spoil them for you. All I can say is that each of them works uniquely and sometimes solving the puzzles gives the feeling of planning ahead the moves of a chess game.

In addition to the funny-sounding trigger words, new chapters introduce various other mechanics, building upon the previous ones and making the puzzles progressively more complex. You will encounter ”conductors“ that let you connect separated letters, “clouds” that let you black out a given configuration of cells, and other interesting concepts.

The book is split into 12 parts: 8 chapters with a total of 80 puzzles, 2 expansions with 10 extra puzzles, Rules that explain all the concepts in the book that have been left to the solver to discover, and Solutions that provide the answers to all puzzles. The parts are separated by beautifully illustrated pages of cute worm-like creatures, called ”Loks”, performing various activities, such as flying in space or working in a factory, on 10 additional solvable grids. Of course, the author could assemble the book just with all the 100 puzzles inside, and it still would have been great, but that extra touch of art is what makes LOK even more special for me.

While the market is currently flooded with all kinds of derivative logic books filled with computer generated Sudokus and Kakuros, LOK differentiates itself as an ingenious passion project of someone who simply wants to contribute to the world of puzzling. You can get the digital version of LOK for free from the author’s website by clicking the button below. If you like, there you can also purchase the physical edition and solve the puzzles the way they are intended to be solved, with pencil and eraser on paper. For those who prefer to keep their puzzle books in immaculate condition, a transparent draw board is included in the package. Thanks!

  • appropriate for all ages
  • more than 90 carefully hand-crafted puzzles
  • surprising mechanics taught through practical solving
  • explained rules and solutions included
  • free e-book version available to download



Beautiful Geometry 1

Since 2018, Catriona Shearer, a UK teacher, has been posting on her Twitter various colorful geometry puzzles. In this mini-course, we cover some of her best problems and provide elegant solutions to them. Use the pagination below to navigate the puzzles, which are ordered by difficulty.

Example Problems

What fraction of the hexagon is shaded?
Which area is larger, the yellow or the red one?
What is the area of the large square?
What fraction of the outer circle is shaded?
If the circle radius is 1, what area is shaded?
What fraction of the decagon is shaded?