Are you a fan of the popular logical puzzle that (0) GOES by the name Sudoku? (1) ............ you're not, the chances are you know somebody who is. Once (2) ............ known outside Japan, this addictive brain teaser has become a common feature of newspaper puzzle pages all over the world. Sudoku's great success (3) ............ much to its simplicity. The game (4) ............ for neither mathematical ability nor (5) ............ knowledge and there are just a few sentences of straightforward instructions to read before you can play. The only skill required is the ability to (6) ............ the difference between nine different symbols, and these don't even have to be numbers. Some clever marketing has helped the game. Western newspapers worked (7) ............ on promoting the game. Without this, it is unlikely that it would have (8) ............ off and become quite such a runaway success. The game also benefited from its Japanese name that made people in many parts of the world regard it as a superior kind of puzzle compared to those you usually find in newspapers and magazines. But the popularity of Sudoku reached a peak in 2006, if the number of hits on one leading website is anything to go by. Newspapers responded by coming up with new kinds of logical puzzles, all with simple rules and Japanese names. But for true Sudoku fans, only the real thing will do.