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Archive for the 'Puzzles' Category

Dumb Ripoff Alert

Friday, January 6th, 2012

I just found a book in the Kindle bookstore that (incompetently) rips off some of my sudoku puzzles. The book is called “The Most Difficult and Hardest Sudoku Puzzles” and is “copyrighted” by one Johnny Cohen. Here’s the cover: The cover helpfully informs you that the book is a BEST SELLER. Here’s a sample of […]

Hexadecimal Sudoku

Tuesday, December 20th, 2011

At the request of a few persistent (and possibly masochistic) puzzle fans, I’ve added four collections of Hexadecimal Sudoku to the puzzle collection. These are 16 x 16 puzzles that use the 16 hexadecimal digits (0-F), instead of the nine digits used in regular Sudoku puzzles. This is a good puzzle to take on your […]

Sudoku Troubleshooter #4 – XYZ-Wing

Thursday, November 24th, 2011

Troubleshooter #4: XYZ-Wing This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. Michael wrote in an email: Dad, Good morning and an early happy thanksgiving. I really enjoy your puzzles and I […]

The Ins and Outs of Slitherlink

Friday, November 4th, 2011

One of the most difficult Slitherlink puzzles I publish is the Laves Slitherlink, which you can find in its own collection, as well as in my variety slitherlink collection. I recently helped a reader, Billy, solve one of these monsters, and I thought I’d share the tips here. We explored a handful of advanced solving […]

Kagen Schaefer’s Pipe Organ Desk

Wednesday, September 21st, 2011

This is undoubtedly the coolest wood working project I have ever seen. A wooden desk whose drawers emit pipe organ sounds ranging over an octave. Open the doors to play a particular melody, and a secret compartment opens. The password can be changed by turning wood screws on the wooden pneumatic logic board, shown below. […]

Interactive Sudoku Beta

Thursday, September 8th, 2011

I’m currently working on an interactive Sudoku page (to be followed by other puzzles as well). If you’d like to play with a very early “beta” version of it, you’ll find it here. The page is designed to work in modern web browsers (Safari, Chrome, Firefox 4+, IE 9+), and also works on iPads. A […]

Sudoku Troubleshooter #3 – X-Wing

Monday, August 29th, 2011

This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. This is a tough puzzle, book 7, puzzle 7. It was submitted by Stephen, who got stuck after solving 4 numbers, like so: […]

Sudoku Troubleshooter #2 – XY-Wing

Wednesday, August 24th, 2011

This is part of a series on puzzle solving techniques. If you are stuck on a particular Krazydad puzzle, drop me a note, and I’ll use this space to help you out. This puzzle is also from Margaret, who got stuck on a Tough puzzle (Tough #4 from book 40). If you’d like to try […]

Sudoku Troubleshooter #1 – Row/Column/Block

Tuesday, August 23rd, 2011

Occasionally, I get mail from fans of the site who need help with a puzzle. I’ve decided to devote the next few blog entries to puzzle solving techniques. If you want help with a particular Krazydad puzzle (especially puzzles that are easier than “Super Tough”), drop me a note, and I’ll troubleshoot your problem too! […]

Galaxy Puzzles

Saturday, August 28th, 2010

The latest addition to my puzzle collection, Galaxies are elegant puzzles in which symmetry forms an essential component. You are presented with a grid containing circles, in seemingly random positions. You fill in the lines of the grid to form an island, or galaxy around each circle. The galaxy shapes must be rotationally (or 180° […]