Book excerpt: Sudoku For Dummies, Volume 2 will offer 240 original and addictive puzzles including new circular and 16 x 16 puzzles to add new dimensions to game play and keep the most avid Sudoku fan entertained. Of the 240 puzzles, 220 are the popular 9x9 puzzles, 10 are 16 x 16, and 10 are circular puzzles. Within each of these categories there are Easy, Tricky, Tough and Diabolical puzzle ratings; and each puzzle is clearly identified with the rating. More than just a listing of puzzles, Sudoku For Dummies, Volume 2 features a chapter explaining how to solve puzzles and the strategies involved. Additionally, readers receive all puzzle solutions in the back of the book. Finally, Sudoku For Dummies, Volume 2 includes a brief history of Sudoku (or Su Doku) for those interested. Descriptions of the newer types of puzzles are listed below. Circular Sudoku (10 included: 3 Easy, 3 Tricky, 2 Tough, and 2 Diabolical) The rules are similar to the normal 9x9 Sudoku but with some important differences. The puzzle is circular for a start, with 8 concentric rings. Each ring must contain the numbers 1-8 and each segment running into the centre of the circle and through to the opposite side of the circle must contain the numbers 1 - 8 and or course there can be no duplicate numbers. 16 x 16 Sudoku (10 included: 3 Easy, 3 Tricky, 2 Tough, and 2 Diabolical) The grid is larger at 16 x 16 and solvers must fit the letters A-F into the grid alongside the numbers 0-9. 16 x 16 Sudoku are more difficult, take more time and are more infuriating than the normal puzzles - but just as addictive!