John Welch writes an excellent blog for advanced Sudoku Solvers called Systematic Sudoku. Every Tuesday he posts a new detailed analysis of a tough puzzle, one of his goals being to understand the comparative difficulties of various sudoku publications. Sudoku difficulty is hard to measure and describe, and different publications (including this website) use different [...]

It’s been a long while since I’ve posted, but hopefully, there are still one or two of you out there who understand the value of a good RSS feed. I’m back to write about a book I’m enjoying, with the following cryptic title: 10 PRINT CHR$(205.5+RND(1)); : GOTO 10 If this line of BASIC code [...]

If you combine a sufficiently large number of (uncorrelated) photos, and choose the images carefully, you can approximate any image you like. This “Shroud of Turin” was made by carefully choosing 300 photographs from a larger set of 20,000 photographs of graffiti. All images come from Flickr and are Creative Commons licensed. The images are [...]

This Penrose Slitherlink puzzle is inspired by David Millar’s “Area 51″ puzzles, which you can find at The Griddle. The puzzle works like a regular Slitherlink puzzle, but with a few twists: The aliens must be kept inside the fence. The cacti must be kept outside the fence. The white circles indicate a straight line [...]

This month, I’ll be teaching two Processing workshops at CRASHspace, the awesome hacker space in Los Angeles. You can sign up for these classes in the CRASHspace store. This is a fundraiser for CRASHspace: all proceeds will go towards paying the rent and such. Each class is 4 hours long, and costs $60 ($40 for [...]

Next Saturday, I’ll demonstrate my musical chess system at the 3rd Annual Handmade Music L.A., at CRASH Space in Culver City. There will be a number of other tinkerer/musicians there as well, showing innovative pieces of homemade music technology, including circuit bending, noisy circuits, repurposed video-games machines, and amplified motors. Hope you can join us! [...]

Lately, I’ve been solving Krazydad puzzles on an iPad, using my finger, or a stylus, rather than printing them out and solving with a pencil. My iPad app of choice for printable puzzles is UPAD, a great little drawing app that works well with PDF files. It is available in both free and paid versions. [...]

Here are six new Slitherlink puzzles for you to try. This puzzle is based on Floret Pentagonal Tiling, which was suggested to me by Danny Sichel. The additional clue styles (ampersand and dollar sign) were inspired by David Millar’s excellent “Area 51″ puzzles, from The Griddle. Fill in some of the dotted line segments to [...]

Dear Krazydad, My husband just started doing KenKen and really loves it. I have a question for you as most of your Inky puzzles seem to have this symbol in them: What does the symbol / mean? Confused Dear Confused, The / symbol is used to mean division (as in 12/4 = 3). It means [...]