Killer Sudoku - Difficult but by no means fatal

Among the Sudoku variations one might come across, we find what is called Killer Sudoku a combination of of Sudoku and Kakuro puzzles. Although the name leads you to believe that the "killer version" of Sudoku would be a great deal more difficult than your Standard puzzle this isn't necessarily the case, as the easier Killer puzzles can actually by a lot easier to solve than most standard Sudokus. Read on to find out more about this Sudoku version. 

Like the basic puzzle game, this version is not a new invention as already in the 90s it was a well known version of Sudoku in Japan. It first went under the name Samunamupure which loosely translates as "sum number place". Akthough "big in Japan" for quite some time, the Killer Sudoku was started to be more well known in English speaking countries as of 2005.

The rules are very much like in the ordinary Sudoku puzzle, with two major exceptions. The first being the presence of something referred to as "the cage", and is the Kakuro or crossword puzzle element that has been added. This is represented either by colors or a dotted line. The second difference is that, unlike normal Sudoku, there isn't a digit pre-filled in any of the squares. Instead each cage has a tiny number somewhere inside it, and the sum of all numbers in the cage should amount to the value of this given number. A cage can consist of a maximum of 9 cells, and a number can only appear once in each cage.

Altohough the Killer Sudoku has been available both online and offline for a while now, many gamers still find them difficult to solve. Others do not even bother to try as they have not understood that solving the Killer verison is not that different from the original Sudoku. The main difference is that they now are given a more and different information in each puzzle.

Here are some sample strategies you can use for getting started on your Killer Sudoku.

•  Look for the ins and outs

It is always sound practise to begin with the obvious – every row, column and grid when added up must become 45. However, this might  not be very much help when the cages fit accurately into every row, column or grid.

•  Finding the pairs

The cages that are easiest to figure out are those that are made up by just 2 numbers. When two or more of these numbers are found within the same column, grid, or row then it is quite a feasible task to begin removing possibilities of paired numbers. Numbers 3, 4, 16, and 17 are usually easy to begin with . If the possibilities are many this strategy works up to a certain point.

•  Working with combinations

Trying out all the possibilities for a specific box can only be useful under the right conditions: if there are many limitations on the combinations, you will most likely be looking at an impossibly huge list of possibilities. Terefore, I would suggest that that you don't use a strong combination as your primary tactic. Instead, you should look for ways in which you can limit the potential combinations. You should begin with the cages that have the highest or lowest sums. because they have the fewest possible number of combinations. For example, the sum 23 split into a cage consisting of three sells, can only contain the numbers 9, 8 or 6.

Despite it's name, Killer Sudoku is as easy to play, and if you've already mastered ordinary Sudoku, you can jump right in and play. If this combination of two different types of puzzles is twice the fun is up to each and everyone to decide, though.

Tip! Shop for Books on Killer Sudoku in Sudoku Hint's online store in association with Amazon. I can personally recommend Will Shortz's Favorite Sudoku Variations as well as the Killer Sudoku 2007 Calendar.