Generating Puzzles

To generate a puzzle, you may use the slider control are the top, moving it left-right to quickly generate a puzzle of an approximate difficulty. Far more interesting, however, is to expand the full generation dialog box and fiddle with the details.

Starts

The number of "starts" in a sudoku puzzle has a small bit of relevance to it's difficulty. When puzzles begin with more than roughly 26 values already present on the board, they are farily easy to complete. Below that, puzzles can be more difficult. Once less that 21 starts are given, puzzles are more difficult in an earlier stage of playing. The mathematical minimum for a sudoku puzzle to have 1 solution is to use 17 starts.

Start Patterns

Certain novel methods of placing starts on the board have arisen over the years in sudoku playing. The placements of starts into a non-random pattern can affect the difficulty of the puzzle, since certain patterns lend more clues to the empty areas of the board than other patterns. For this reason, when exploring the limits of your sudoku-solving skills we recommend leaving the pattern on "Random".

Hide a 1..9 Sequence

Also, hiding a 1-through-9 sequence on the board in a straight line, (in any direction, either ascending or descending) can make a puzzle more interesting to solve. But it too will take away from the pure solving strategy of sudoku puzzles.

Minimum Number of Moves

To solve a puzzle with 40 blank cells, you would need to make 40 "moves" of entering the correct answers, at a minimum, to solve it. Likewise, if you have a puzzle with 30 "starts", the remaining 51 cells are empty, and require 51 moves to solve the puzzle. If you ask Sudoku Koubou to require more than 51 moves, you are asking for it to build a puzzle where it must guess and number from a set and then back up to make another choice.

For example, if a puzzle has 20 starts, and takes 61 moves, and you ask Sudoku Koubou to require 100 moves, then it will attempt to build a puzzle that requires guessing and backing up. If these settings are combined with some (or all) of the Solving Techniques, then you are requesting that even with the selected logic, Sudoku Koubou must guess and back up. These can be difficult puzzles indeed, but may take a long time to build.

Required Solving Techniques

Sudoku Koubou solves each puzzle it generates using the logic modules you turn on or off in this section. When you employ each of these modules, you can dramatically affect the difficulty of the puzzles generated. Each of these solving techniques can fill in empty spaces of a puzzle, but each takes a different amount of time to discover the best answer, and some are considered "more difficult" to perform by a typical sudoku player.