I finally got around to posting a sample Whodoku puzzle. Enjoy!

Quoted: Whodoku - Sudoku with Personality by Roy Leban. Famous names and intriguing riddles add spice to these popular sudoku puzzles. Sterling book by Roy Leban. Similar to Wordoku and Letter Sudoku.

There are only 5 billion essentially distinct Sudoku puzzles (solutions) (proof here using Group Theory and Burnside's Lemma).

My first puzzle book just came out.

Read my blog post on thistangent.com for some more information.

Quoted: Who knew that sudoku could have so much personality? They can—when famous names and intriguing riddles add spice to these popular puzzles. Here’s how it goes: on top of the page is a fun, partially completed clue about an unnamed person; for example, “He was in _____ for 27 years before being elected president.” There’s also a series of nine letters to use in solving the “who-doku,” and the grid itself has a number of circled spaces, as well as shaded areas. When it’s totally filled in, the circled letters provide the answer to the clue, while the shaded ones reveal who the person is. So the solution to the question above is, “prison” and the man is question is Nelson Mandela.

Interesting article on rating the difficulty of Sudoku's and various solving methods (including a short backtracking program written in Ruby).

Pretty decent book on how to solve Sudoku's. I got mine from the author and my wife has learned a lot from it, so I just bought one for my mom.

Quoted: Here it comes: a revolution in sudoku solving! This is by far the most complete guide to cracking these addictive puzzles ever produced, with tricks even the experts won’t know. While most books might have a few pages of introduction before proceeding straight to the sudokus, this one covers it all: hidden pairs, naked pairs, X-wings, jellyfish, squirmbag, bivalue and bilocation graphs, turbot fish, grid coloring, and chains. Every single one is here, and much more too, including the exclusive Gordonian logic methods (Gordonian rectangles and Gordonian polygons) that will turn even the hardest puzzles into a breeze. Of course, there are hundreds of sudoku for practice. A very special addition is a reprint of the very first sudoku ever published in 1979, from Dell Pencil Puzzles and Word Games magazine!

My friend Roy's new puzzle book. You can pre-order from Amazon now.

Quoted: Amazon.com: Who-doku: Sudoku with Personality: Books: Roy Leban by Roy Leban

Quoted: The undisputed grand puzzle master of Su Doku, Tetsuya Nishio, says he has a ‘dreadful challenge’ for Times readers: a worthy successor to the puzzle that has so infuriated and entertained you

My sister, Catheryn, is hooked on these. Tired of vanilla Sudoku? Go Samurai Sudoku!

Quoted: Samurai sudoku puzzles consist of five overlapping sudoku grids. The standard sudoku rules apply to each 9 x 9 grid. Place digits from 1 to 9 in each empty cell. Every row, every column, and every 3 x 3 box should contain one of each digit.

redotting: Catheryn

Quoted: Samurai Sudoku puzzles and solver with hints and step-by-step solutions. Print samurai sudoku puzzles at several grid sizes.

sudoku site that lets you write in the little numbers.