Sudoku, a puzzle game created by American Howard Garns in 1979, became wildly popular in Japan during the 1980s and 1990s before becoming a worldwide pheomeonon in this decade. Sudoku is a type of “Latin Square” puzzle (Sudoku means single number in Japanese) that involves the placement of numbers from 1-9 in a series of boxes. A Latin Square is an array of spaces where individual numbers are used only once to fill them. There are 81 total spaces on a Sudoku board. 9 3x3 squares are assigned in a 3x3 arrangement to form one large 9x9 puzzle. The creator of a particular Sudoku puzzle gives away a number of answers and the player is left to fill in the rest of the blank spaces using logic and reasoning, given the rules of the game. A Sudoku puzzle is correctly solved when each row and column features each digit placed exactly once. Furthermore, each of the 9 3x3 grids that make up the entire Sudoku puzzle can have each digit placed only once as well. Each Sudoku puzzle has exactly one correct solution. Soduku was initially published in Dell Magazine, a weekly magazine featuring crosswords and other assorted puzzles. The game was initially entitled Number Place, but received its more commonly acknowledged moniker when it began to become popular in Japan. The difficulty of each individual puzzle varies and is determined by a computer that assigns how difficult the answer is to ascertain. Surprisingly, the difficulty of the solution is not just related to how many initial free answers the game’s creator gives. More important than that is how the free spaces are arranged. If they are kept apart, Sudoku can become incredibly difficult. The relevance and the positioning of each free space is used to determine how challenging the puzzle is. In some cases, computers aren’t used to estimate the difficulty of the puzzle. In some instances, human solvers are assigned puzzles and the median time to solve each individual Sudoku puzzle accounts for its difficulty. There are many examples of unsolvable Sudoku puzzles. In fact, a board with 77 givens can be presented with no unique solution if the givens are arranged properly. This is one of the biggest challenges facing Sudoku puzzle makers. The puzzle maker must not only provide a Sudoku board with one unique answer, but also with a logical process that can be followed from beginning with the givens through the entire solution. Little assumptions can derail a Sudoku puzzle so it becomes critical to be able to think exactly like the person trying to solve the puzzle. No matter how difficult the logic, there must be no interruption in the thought process flow of a Sudoku puzzle. The puzzle can be made incredibly difficult, but there must always be a way for someone to arrive at the answer. As Sudoku has gotten more popular, there have been more and more exotic versions of the game created. Some games with larger boards and 9 9x9 arrays have been made. The game doesn’t objectively changed, but there are so many more interrelationships within the game that some incredibly difficult variants have been created. Regardless, it’s obvious that Sudoku is going to remain popular in the US and around the world.
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