Have you heard of the paper and pencil puzzle game called Sudoku that has become very popular lately? If you haven't heard about Sudoku, keep reading; you're in for a treat! One recent night when I arrived home, a neighbor was in the lobby of my apartment building playing a Sudoku puzzle out of a newspaper. He was stumped and he asked me for help. I had no clue how to play and not enough time to think about it then, but I did try to help my neighbor out with his dilemma a little. Later that night, I got curious about Sudoku, so I decided to see if it was available for the Mac. A quick Google search lead me to Gamehouse.com where I found a great Sudoku game for Mac users.

This game is available as a 3.1MB downloadable file. The file was easy to install. You can play it for about half an hour for free, then it requires registration to play any further. Sudoku's rules are easy. The game board contains nine 3x3 grids. Each grid is divided up into nine boxes for a total of 81 individual boxes. Several of these boxes will contain a computer-generated number from 1 to 9.

The object of the game is to place one number from 1 to 9 in each empty box so that each number occurs once in each row, column, and 3x3 grid. Each game has one unique solution which can be found by using a few simple rules of logic. These logic rules are explained in the game's help window.

The computer places one or more markers in each empty square. A marker is a number in a tiny font size that may or may not be the correct solution for a given box. One hint in each box will be correct, but which one?

GameHouse's Sudoku is timed and it offers ten levels of diffi- culty. Each level of difficulty controls the amount of hints that appear in each square. The more difficult the level, the less help- ful hints become. Level 1 is the easiest; level 10 the hardest. You play against the clock. The faster you complete a game, the higher your score. You can compare your scores online with other GameHouse Sudoku players.

Playing Sudoku is easy and math skills are not needed. You get a list of numbers on the left side of a window and a game board on the right side. To place a number on the board, you click on that number in the list or type it on the keyboard, then use the mouse to click on the box where you intend to place that number. That's it!

A button is available to undo mistakes. You are not penalized directly by using the undo feature, but the clock keeps ticking, as it does if you pause the game.

You can tell if you are going astray with number placement because you will eventually see one or more boxes with no markers or hints and/or boxes with two identical markers. No box should have duplicate markers. Any box without at least one marker should already have a number placed in it by you or the computer. If you run into these kinds of difficulties, it means your logic is flawed. Numbers that conflict with other numbers will turn red. Numbers that do not conflict with other numbers turn white. Numbers in yellow text were placed on the board by the computer and can't be touched.

GameHouse Sudoku has only a few controls and no software preferences. The background music, which is on by default can be turned off. You can increase the degree of difficulty at the beginning of a game. You can also toggle on and off the marker hints at any time. The board has buttons to reset the game, clear an erroneous box, and undo a number placement. You can also print a board to play Sudoku without a computer. Right now, I am only at level 3. I cannot imagine playing without the markers, but maybe I will improve enough to do that by the time I get to level 10.

I highly recommend GameHouse Sudoku. Sudoku is a fun pastime for people of all ages. Sudoku provides a fun way to exercise your mind, which is beneficial to everyone, especially kids who need fun mental exercises to develop their reasoning skills. Be warned; however, that Sudoku is very addictive!