Sudoku is the popular logic based number placement puzzle game invented by American architect Howard Garns (and first published under the name of 'Number Place') in 1979. It was renamed Sudoku (which means 'Single Number' in Japanese). Sudoku became wildly popular in Japan before coming home to the United States.
There are several variations of Sudoku, but the 9 by 9 grid with 3 by 3 regions which you see in many newspapers is by far the most common. As one website says 'Sudoku is easy to learn, but difficult to master'. Sudoku is good mental exercise.
I really enjoy playing Sudoku. I like playing it hard copy because I do it in bed almost every night before I go to sleep. What I don't like is waking up in eraser shavings. That is why I was so excited when I got a couple of Wipe-Off Sudoku games in my Christmas stocking.
I have the 'Hard' and 'Expert' versions of the wipe-off game. 'Easy' and 'Medium' are also available. The Hard usually has between 28 and 32 of the 81 squares populated. The Expert usually has 28 or 29 of the 81 squares populated.
Each spiral bound wipe-off game pad contains 25 games. The solutions are included inside the back cover. A small grease pencil is supplied along with a convenient holder attached to the game pad.
I prefer the Hard version best because, in general, you can use true logic to solve the puzzles. With the Expert version I sometimes need to revert to guessing and brute force.
I enjoy playing Wipe-Off Sudoku.