The bookstores are being flooded with Sudoku books. It is just a year now since I first saw Sudoku puzzles showing up in a little freebie newspaper. As time went on, books started showing up. The number of puzzles in a book increased from 100 to 1000, some books give a bit of history with claims of being invented in Japan but the puzzle has been around in America since the 70’s, although under the name of Number Place. Some books give very little in the way of hints and solving methods while others do a much better coverage in this area. This is more important to someone just starting to do these puzzles. Nearly all books have puzzles organized in 3 or more levels of difficulty. Also books vary greatly in the quality of paper, printing and size of the cells and book size and binding. (See some of my other reviews on Sudoku books for more information on the sort of things to consider when choosing one book over another). The Ultimate Sudoku Challenge is different enough that I decided to discuss it. This edition was published by Sterling in the US and Canada in 2006 and in by opinion is one of the best publishers of puzzle books in North America. The book was published earlier in Great Britain in 2005. There are 200 puzzles in the book and are mainly on the medium to difficult level. Usually the givens in a Sudoku puzzle are symmetrical but here many are not, maybe this tends to make them more difficult. With 1 puzzle per page, the size is good and the printing and paper quality is very good. I was quite taken in that it is claimed that the puzzles were all created by hand as opposed to computer generated. In my copy I could find no name of who created the puzzles but here it shows the name Nikoli. This is probably correct as that name has been on several other Sudoku books. Mystery solved! Now to what is different about this book. We are seeing all kinds of variations to the basic 9X9 cells and all sorts of other Grid type puzzles. However, what we get here is 10 Mega Sudoku’s with 25X25 grids. Some time ago we started to get 16X16 but this is a big leap. The Megas are on the same sized pages as the 9X9 and as such way too small. The only hope is to draw up your own 25X25 Grid. I would suggest 1/2X1/2 inch cells, therefore a grid size of 12 and 1/2 inches by 12 and 1/2 inches. I don’t think that is even large enough because on average there are about 240 givens in each puzzle at about 10 per row leaving about 15 unknowns. So you are going to be trying to get a messy bunch of possible in a cell. Get the drift? With standard 9X9 grid puzzles there are from 18 to 25 givens out of 81 with the first Mega there are 242 of 625 given. Like other reviewers, I have yet to aggravate myself with attempting to solve one yet.