Sudoku (Number Place) puzzles

Select the Sudoku template in the New Puzzle window to make one of these. The standard size is 9x9, however you can also make larger sizes using an extended alphabet of symbols. The program will place the numbers automatically for you. The starter letters (givens) are shown in blue and will be visible in the puzzle when you export (as shown on the left).

You can specify a desired difficulty level and whether you want the givens symmetrically placed. To generate a new fill for an existing puzzle use the AutoFill button on the toolbar.

The solving applet supports this puzzle style, see the Export interactive crossword topic.

For an introduction to the Sudoku see Wikipedia .

Puzzles are rated as “easy” if they can be solved by repeatedly placing single number candidates in squares. “Medium” puzzles require use of sector elimination (e.g. if a “2” can go in two squares in a row, and both squares are in the same block, the “2” in that block must be in that row so ”2” may be eliminated as a possibility for the other rows in that block). “Hard” puzzles require use of disjoint subsets (e.g. if “23” and “235” are the possibilities for two squares in a row, and “2” and “3” cannot go anywhere else in the row, “2” and “3” must occupy those two squares, and hence “5” may be eliminated). “Very easy” are easy puzzles containing redundant givens (i.e. numbers that could be worked out from the other given numbers).

Select Check sudoku on the Grid menu (or the toolbar button) to check a Sudoku to make sure it has a unique solution and give it a difficulty rating. If there isn’t a unique solution a few ambiguous squares are highlighted. The “Very hard” rating means that it cannot be solved by repeated use of the methods listed above, and is likely to be too hard for most publications.

The starter letters (givens) are automatically set to have “Letter visible in puzzle” in Square properties. and are shown in blue for editing purposes (you can change the color in preferences). They will appear black by default when you export. If you’d like to change the color used when exporting select the squares (use select all - letters visible in puzzle on the Edit menu) and then use Square properties. on the Edit menu to change the text or background color.

The default numbers or characters used for the Sudoku are specified in the same window as the size in the New Puzzle wizard. You can edit these, e.g. if you wish to use 9 different letters rather than the default set of numbers 1-9.

If you want to include a particular sequence of letters or characters in the grid, use the New Puzzle window to make a new puzzle, then press Cancel when you get to the Sudoku Fill box. This gives you a blank sudoku grid. Just type in the letters where you want them in the grid, then use the Fill button on the toolbar to complete the grid.

To make larger puzzles than the standard 9x9, click the Other size expansion box in the New Puzzle wizard. Instead of numbers and single letters, you can also make Sudoku using any other number or text symbol for each equivalent entry. You can select to use Letters/Numbers (standard), a custom set of short words, or use numbered squares (e.g. for a 4x4 puzzle, using numbers 1..16 in each square, rather than 1..9A..F).