Erasable Games Weblog

(Sudoku in words and pictures)

Archive for August, 2007

Braille Sudoku

Sunday, August 26th, 2007

Braille Sudoku

This weekend, my daughter fell off a ladder and broke her ankle in two places. The emergency room in the hospital awarded her a splint along with crutches. As a newly handicapped person, she is learning the ease and inconvenience of this method of transportation.

And so it is with low and no vision (which my mother suffered from). Braille seems to be the standard way of writing things down that is accessible to the visually impaired. This kinesthetic language was created in 1821 by Louis Braille for non-linear reading and writing. It is the first binary encoding of the characters of various languages. See Wikipedia for more information.

I thought it interesting to see how Sudoku puzzles could be adapted for use in Braille. Obviously a board is not the best medium for this. Paper or parchment may allow one-time use. There do exist refreshable Braille Displays, which can serve the same purpose as erasable white boards. Unfortunately, the current models are limited to 80 cells at a maximum and are expensive to buy.

I feel strongly, that the mind and the active senses are quite adaptable. I hope Sudoku arrives in the world of the blind to offer mental exercise and logical satisfaction. Consider this my push in that direction.

Illicit Sudoku = Proper Hitori

Sunday, August 19th, 2007

Illicit Sudoku = Proper Hitori
I discovered this distant cousin of Sudoku in the newsgroup rec.puzzles a couple of weeks ago. Kevin Stone has provided an enhanced user interface with notes for doing daily Hitori puzzles on his website His site provides 3 sizes: 5×5, 7×7 and 9×9. These puzzles change daily. Previous Puzzles revert to Neil Berget’s beta website An archive is not yet available. offers 5×5, 8×8 and 12×12 size puzzles, as well as a tutorial on how to play.

Hitori is Japanese for “Let Me Alone”. More information is in the Wikipedia Article. The Nicoli Company Website has an animated (flash) tutorial.

The rules are straightforward. Shaded cells cannot be contiguous. They are either separated by a non-shaded (‘white’) cell or touch at their corners. Non-shaded cells, on the other hand, must be contiguous (e.g. at least one side must touch another ‘white’ cell’s side.) The result is that when a puzzle is solved, one can travel a connected path of ‘white’ cells. Puzzles provided by these web sites lead logically to unique solutions.

Hitori exercises your brain differently than in Sudoku. It’s almost as if your luggage is too full to close and you must toss expendable articles so that it fits. I found it necessary to go down each row, making the numbers unique, then going across each column. When this is done, I checked that I didn’t isolate any ‘white’ cells. That seemed to be sufficient to form a correct answer.

Both websites have a (partial) solution checker and it can show any mistakes that are evident as well as if it is all correct. I definitely enjoy this variation on a Sudoku board.

Rotational Sudoku

Sunday, August 5th, 2007

Rotational Sudoku

That is the question, as Tom Dickson of Blendtec Blender Video Fame often asks. The link shows a short video clip of an iPhone being put to that question. Due to budgetary and technical limitations, I am only willing to show pictorially how a Sudoku Board gets brought to its numerical knees.

I hope you all enjoy this as much as I did while creating it.