When I first read the following words in Roland’s interview, the first thing that came to mind was to work with him in a book, and so this book was formed: “I enjoy Skyscrapers puzzles more than any other type (solving and creating alike). I am creating large quantities of them (I do not know what to do with all of them – maybe they will appear in a puzzle magazine or book someday)”.
As stated in his foreword, this book contains excellent puzzles of a puzzlemaker who has chosen to specialize in skyscrapers puzzles. Honestly, as an editor of the book who has solved every single puzzle in it, I can say that this book changed the way I handle skyscrapers puzzles. I got the opportunity to experience many different methods he has used, and this also changed the way I prepare skyscrapers puzzles.
The size of the book is 115×160 mm. It contains classic skyscrapers and 3 types of variations in 128 pages. There are 62 Classics, sizes vary between 4×4 to 8×8; and there are 18 of each variant (Irregular , Diagonal, Gappy) sizes vary between 4×4 to 7×7. So in total it makes 116 great puzzles, all handmade by Roland.
Cover design is made by Gökhan Okur and interior design is made by Erhan Seyis. There is a King Kong reference in the cover, but it displays a view of İstanbul rather than New York. And the building next to King Kong is Galata Tower. The back of the cover represents a hedgehog who stands against King Kong, and he is symbolizing Roland (His nickname Hausigel partially means hedgehog in German).
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“Why do I love skyscraper puzzles?
I have been asked the above question many times. In our sudoku era, it is not easy to become really fascinated by a different puzzle type, but that is exactly what has happened to me for some years now. Basically, skyscrapers are the only puzzle type I seriously invest time in, and people are usually curious why this is the case. Well, let me try to explain.
Classic sudokus – I will assume in the next few paragraphs that you are at least a little familiar with this most popular type of logical puzzles – are somewhat rigid, as far as puzzle creation is concerned. The reason lies in the mathematical structure of the (classic) sudoku grid. Given a sudoku, swapping a couple of rows or columns does not make a “real difference”, in the sense that you would be able to solve the new puzzle the same way as you would solve the old one, just replacing the rows/columns in question at every step. Likewise, the nature of a sudoku does not really change if you permute the digits. In mathematical terms, such two puzzles are “isomorphic”, meaning that they become identical after a couple of rather elementary transformations of this or a similar kind.
The consequence is that there are not that many “really different” sudokus at all. Naturally, the number is still way too large to print them all, but if we restrict our attention to classic sudokus with a minimal number of clues (17) for the moment, their number is considerably smaller. As far as I know, about 50000 have been found so far, and it is unlikely that the magnitude of the total number will change. When solving sudokus, this is hardly a problem, but as far as designing puzzles is concerned, I am sort of scared that the puzzle I come up with is already published somewhere and well-known to the puzzle community. Call me paranoid, if you like.
Skyscraper puzzles are, at least in my view, much more flexible. Swapping rows or columns will make a huge difference, as will permuting the digits. Of course, the danger that I create the same puzzle twice is still present, but it appears much smaller. When it comes to solving skyscraper puzzles, you will notice from the part on solving techniques that sudoku solving steps are part of the process – the last part, usually – hence I like to view skyscraper puzzles as a member of the family of “sudoku-like” puzzles (enter numbers in a quadratic grid such that numbers do not repeat in any row or column, plus some additional restraints).
Apart from the fact that skyscrapers, like sudokus, allow a large number of variations, I find it extremely challenging to come up with some new solving steps or at least new combinations of solving steps – something that is almost impossible with classic sudokus. In this regard, I believe that skyscraper puzzles have much more potential than sudokus (although I might be slightly prejudiced in favor of skyscrapers from my ongoing work with them). Anyway, I feel it much more stimulating to both design and solve skyscraper puzzles than sudokus.
Please do not get the impression that I want to scare you off from sudokus. Like all logical puzzles, they keep your mind going, which should be the most important point of all. Skyscrapers are probably new for you, but rest assured that they can challenge your brain as much as sudokus or any other type of logical puzzles. It is my hope that, after going over the puzzles in this book, you enjoy skyscraper puzzles like I do.
I am indebted to my brother Ulrich, who has not only inspired me to join the community of logical puzzles at all and helped me to become a puzzle author, but also checked every single puzzle in this book. (I usually place the burden of testing new puzzles on him.) His help and support is central in all my puzzle activites.