Change History

V5.3 2017-02-28

  • Allow clue cells to be coloured.
  • Added highlighting of buddies of the selected cell. This is turned on by default, but can be turned off from the options dialog.

V5.2 2017-01-02

  • Changed the default save location to be in the folder "My Documents\SadMan Software\Sudoku\", instead of the application installation folder.
  • Added an option to the Print Several Puzzles dialog to cause the printed puzzles to also be saved to the default save location with a file name based on the current date and time.

V5.1 2016-06-26

  • Restore the functionality of the A1-I9 coordinate system. This has probably been broken since v3.5, released in September 2009.
  • Fixed the display of the coloured cells shown in the hint function for when a full chain contradiction is found when using the colouring solving technique.

V5.0 2016-05-05

  • Ensure the pencil marks are cleared when a solution number is entered into a cell. This doesn't effect the display to the user, nor the automatic solver, but previously, pencil marks could be saved in the .SDK file for a cell that had a solution number. This no longer happens.

V4.9 2015-11-22

  • Fixed a bug that allowed Sudoku to try to find a puzzle that requires forcing chains to solve, even though there are none ever since the introduction of the XY-chains solving technique.

V4.8.2 2015-06-14

  • Corrected the cells listed in the solution log for the hidden subset solving method.

V4.8.1 2015-05-12

  • Added the new hint highlighting to the XY Chain solving method that was missed from version 4.8.

V4.8 2015-05-01

  • Modified the hint system so the hints are initially less specific, but give the same level of information eventually. See FAQ 26 for more details. If you have any comments about this functionality, please comment on this thread in the forum.

V4.7 2014-08-11

  • Changed the order that two kinds of colouring are evaluated. Simple "double-exclusion" is now checked for before "full-chain contradiction", as this is simpler to spot. This probably won't make much difference to most colouring cases.

V4.6 2014-01-17

  • Corrected a minor fault that caused correct numbers to be displayed as incorrect when the puzzle was imported from an OCRed image, and then manually corrected.
  • The background colour of pressed buttons on the highlight and effects toolbars is now darker to make it easier to see which buttons are in the down position.

V4.5 2013-10-24

  • Corrected a minor fault that prevented the retention of the configuration option added in version 4.4.

V4.4 2013-09-30

  • Added a new configuration option to control whether number entry should use the highlighted number. This functionality was introduced in v4.3, but some users were not happy with its operation.
  • Added an option to print empty grids. These can be used as a worksheet to assist when solving offline.

V4.3 2013-07-08

  • If you have a single number highlighted using the highlight toolbar, double-clicking a cell will enter that number, provided it is allowed by the pencil-marks. If you have none, or more than one number highlighted, double-clicking will enter naked or hidden singles as before.
  • Similarly, if you right-click a cell while a single number is highlighted using the highlight toolbar, this will toggle the pencil mark for that number.
  • Fixed a fault in the "positional-click" input method that stopped it being used to enter clue numbers.
  • Added "Go to Sudoku Home Page" and "Go to Sudoku Support Forum" options under the help menu.

V4.2 2012-08-08

  • Maintain the user-defined custom colours between the various colour dialogs and between separate runs of the application.
  • When the solving timer is enabled, it now saves the solving time to the SDK file, and the timer continues from where it left off when this file is re-opened.
  • Corrected a problem that occurred when a puzzle collection file had additional text after the Sudoku definition.

V4.1 2012-01-30

  • The application executable is no longer compressed, as compression seemed to result in a minority of virus scanners generating a false detection.
  • Change to the positional-click input method so that holding down the control key and clicking toggles the colour corresponding to the position numbers 1 to 6. Clicking positions 7, 8 or 9 clears the colour.
  • Fixed a bug that the incorrect number marker was not reset after an undo operation.
  • Fixed a bug that it was not possible to deselect a cell once the puzzle was solved.

V4.0 2011-11-01

  • Added the ability to scroll through the highlight toolbar buttons by pressing the [ and ] keys.
  • Added the "positional click" input method. This is an input method that enters numbers based on the position of the click within the cell. See the online help for more details.

V3.9 2011-08-08

  • Added two more colour options, bringing the total to six.
  • Fixed a bug that could result in some grades being displayed incorrectly when printing puzzles from the library.

V3.8 2011-07-04

  • Added the option to show or hide pencil marks. This purely controls whether they're displayed, and not whether they're updated or not.
  • Added the ability to create a bookmark to save the current state of the board. You can create a bookmark, try a particular solving route, and if it doesn't work out, restore to the point when the bookmark was taken.
  • When single stepping, the explanation of each step is shown in the status bar.
  • Fixed a bug that could result in the same puzzles being printed on successive runs of the program. This fault was introduced in version 3.7, and only happened if background puzzle generation was disabled.

V3.7 2011-01-22

  • Improved the behaviour when pasting from Excel so that consecutive tab separators correctly result in an empty cell.
  • Corrected a problem when the "not solved" grade prevented puzzles with a specific technique from being found in the library.
 

V3.6 2010-11-01

  • Added another variation of the colouring technique - multi-colouring type 1. This allows all cells of one colour to be eliminated because of a with another separate chain. (See the description of the colouring technique for details.)
  • Modified the puzzle library so that it holds the same number of each grade. It is initially created this way, but over time, the most used and/or the hardest grades to generate, could be under represented. This meant that if you always played puzzles of one specific grade, the library could actually contain fewer of that grade.
  • Added another grade for puzzles that Sudoku cannot solve without resorting to trial-and-error. Puzzles of this grade are shown as "not solved". This is in response to the increasing number of users asking for even harder puzzles.
  • Increased the number of puzzles held in the library from 1000 to 2700, so it now holds 300 of each grade.
  • Added the ability to undo hints. Previously, clicking UnDo after a hint would undo the move before the hint.
  • The puzzle symmetry option has been removed, since I discovered that reflective symmetry puzzles only form around 1% of those generated.
  • Corrected a fault when printing puzzles from the library when the library contained no puzzles of the specific grade(s) requested, it now displays a warning message instead of printing an empty grid.

V3.5.1 2009-11-16

  • Corrected a fault that could cause a "range-check error" if the pop-up menu was enabled in place of the number-selector.

V3.5 2009-09-23

  • Corrected the colouring routine as it would previously miss possible eliminations from double-exclusions between a column / row and a block. (My thanks to John Davenport Scheuer for reporting this fault.)
  • Added the ability to control the delay between clicking the display and the appearance of the number selector. When using Windows Vista, some people had problems double-clicking to enter naked or hidden singles because Windows Vista behaves differently from earlier versions of Windows and does not pass clicks through transparent forms (such as the number selector.) Increasing this delay can make double-clicking easier.
  • Made it possible to double-click the number selector to enter naked or hidden singles. If the appearance of the number selector has interrupted a double- click sequence, double-clicking the selector itself is now the quickest way to enter the naked or hidden single.
  • The trial-and-error solving technique has been improved.
  • Modified the glyph for the Highlight Incorrect Numbers option to reflect the new method of indicating incorrect numbers.
  • Modified the handling of translations with inserted fields to make the positions of the inserted text more flexible. If you use one of the translations, please download and install the latest version.

V3.4.1 2009-04-01

  • Corrected a fault that prevented the opening of Sudoku collection files (*.sdc)

V3.4 2009-03-29

  • Changed the way in which incorrect entries are indicated. Incorrect numbers (or eliminating an incorrect pencil mark) are now indicated by a coloured diagonal (default colour is red) from top-left to bottom-right. This is to ensure the indication is visible even when a custom highlight colour scheme is in use.
  • Added a "System Information" option onto the help menu. This copies some system information and the current configuration to the clipboard or saves it to a file. This is to assist with any problems that may be specific to your configuration.
  • Added a "Buy Now" option to the help menu. This is not shown when the application is registered.
  • Changed the default check-for-updates option from "never" to "weekly".
  • Corrected a fault that caused the XY chain allowed state to not be saved correctly on the New puzzle tab of the options dialog.
  • Made the numeric keypad "-" behave the same as the "-" key on the main keyboard, so it also selects pencil-mark mode.

V3.3 2008-11-21

  • Rationalised the printing, so that the displayed puzzle is always printed just as it is displayed, i.e. what-you-see-is-what-you-get (WYSIWYG.) Removed "print effects" and "print highlight" options, as they are now redundant.
  • Changed the numbering of printed pages when solutions are printed, so that it does not re-start at page 1 for the solutions.
  • Prevented the highlight option from colouring empty cells unless the pencil marks are displayed.
  • Corrected three untranslated strings, two for undoing auto-completion of naked and hidden singles, and the third giving the coordinate format in the solution log.
  • Expanded Library Statistics, Edit Puzzle, and Message Dialog forms to prevent truncation in some languages.
  • Prevented an access violation that could occur when printing multiple puzzles with full-cell-highlighting enabled.

V3.2.1 2008-10-12

  • Corrected a fault that prevented the timer from pausing when focus shifted to another application.

V3.2 2008-10-10

  • When the number selector is shown after a left-click on a cell (ready to enter "big" numbers) right-clicking the number selector will now toggle pencil marks instead. Additionally, the number selector will not close if the control key is pressed while it is clicked, allowing other pencil marks to be toggled too.
  • When printing the current puzzle, also print the solution if this option is selected.
  • When opening files, or pasting from the clipboard, it now recognises additional formats containing pencil marks.
  • The puzzle library is now updated automatically when upgrading to a new version.
  • Added Clear and Random buttons on the Advanced Colours dialog.
  • Added a configurable background colour for the selected cell.
  • Changed the default colours for clue cells to remove the pale yellow background.
  • Now installs with an initial full puzzle library - simply to improve the experience of users installing for the first time.
  • Added the missing XY chain to the solving technique selection form.
  • Corrected a minor fault with the Puzzle Collection form when printing from puzzle collections.
  • Corrected a problem that could result in the same puzzles from the library being printed more than once.
  • If printing an empty grid, don't print the solution!
  • The timer is now paused while a dialog is shown, or if you navigate to another application.
  • Corrected a problem with the hint function that sometimes prevented it from colouring all the appropriate cells for some block/block interactions.

V3.1.1 2007-12-05

  • By popular demand... reversed the change that caused the "effects" toolbar to only use existing pencil marks. If the cell contains no pencil marks at all, the effects are shown based on the single rule of Sudoku.

V3.1 2007-12-03

  • Limited the length of XY chains to 12 cells or fewer, or else the XY chain solver could recurse far too deeply during puzzle creation, using an excessive amount of time and processing power.

V3.0 2007-12-01

  • Added the XY-wing solving technique.
  • Added the XYZ-wing solving technique.
  • Added the XY-chain solving technique.
  • Added the ability to colour different numbers in different colours. See the [...] button next to the default highlight on the colours tab of the options dialog.
  • Added the ability to highlight multiple numbers at once. To highlight a second (or third, or fourth etc) number, hold down the control key while clicking the highlight button. (You'll probably want to assign different colours to each number first, see the previous change.) Sorry, but there isn't a keyboard short-cut for this function.
  • When printing puzzles from the library, give the option of printing several copies of multiple pages, along with their solutions.
  • Added the ability to load and print from Sudoku Collection (.SDC) files. These are files that can contain many sudoku puzzles. This allows for a collection of puzzles that aren't deleted as they're solved. (Contrast this to the library which is a temporary storage place for puzzles that are yet to be played.)
  • Added the ability to save puzzles in Simple Sudoku and Sudocue formats. (It was already possible to load puzzles in either format.)
  • Added comma-separated and tab-separated clipboard formats. The latter is useful for pasting into spreadsheets.
  • The Count Solutions function has been speeded up considerably.
  • It no longer de-selects the "enter pencil marks" option when the puzzle is completed.
  • It no longer de-selects any highlight when all pencil marks are deleted.
  • The "effect" buttons now show effects strictly according to the cell content and pencil marks. Previously, if there were no pencil marks, it would create a set from the single rule of Sudoku, and then highlight from them.
  • If you use a character such as X to represent empty cells, counting and then showing the solutions could omit one of the solutions and show the puzzle instead. This has been corrected.
  • The copy-image-to-clipboard function now excludes the area surrounding the puzzle from the image.
  • Fixed the missing "untranslation" of menu options when English is chosen instead of the default language for the current locale.
  • Fixed a problem with drawing menus under Windows Vista.
  • When displaying the number selector, don't attempt to use the built-in transparency of newer versions of Windows unless running in 32 bit colour mode.
  • Corrected an occasional problem with the chain reported for colouring. The eliminations were correct, but the chain was reported incorrectly.

V2.9 2007-01-05

  • Added a new form to show some statistics on the puzzles in the library.
  • Added the ability to print up to six puzzles from the library.
  • The main window is set to re-appear in the last position it was used. If it was last displayed on the second screen of a dual-screen system, then the second screen was removed, this could result in the main window not being visible at all. It is now checked that the main window is on screen at start up.
  • Allow "dot-notation" for pencil marks. This causes pencil marks to be shown using dots rather than numbers.
  • Allow each number, whether a clue, big number or pencil mark, to be shown in a specific colour.
  • Allow the selection of a second cell and clue background colour that is used for odd numbered blocks.
  • Made the number selector ignore clicks until it had faded in more than half-way. Occasionally, a selection could be made before the selector was even visible.
  • It now remembers the printer you last selected.
  • Improved the description of the coordinate format added to the solution log, as the original description was ambiguous for A1 - I9 format.
  • If you exit with the puzzle unsaved, you're asked whether you want to save the puzzle before exiting. If you select yes, but then cancel the save dialog, the program exited anyway and changes to the puzzle were lost. The program will no longer exit in this situation.
  • Occasionally, during the puzzle generation process, a part-completed puzzle could require deep recursion to solve and/or count the number of solutions. This could sometimes lead to excessive memory and/or CPU usage. This has now been prevented.
  • Show user-specified cell background colour even if the cell content is incorrect.
  • Corrected a bug in the optimisation that could cause X-wings or swordfish to be missed occasionally.

V2.8 2006-09-01

  • Trivial grade has been renamed to Simple.
  • Added the ability to specify whether a simple grade puzzle should require only naked or hidden singles. Depending on how you like to solve sudoku puzzles, you may look for naked or hidden singles before the other. Naked singles are easier to spot if you use a computer program to keep the pencil marks accurate, but if you prefer to solve entirely by hand, you'll probably look for hidden singles before naked singles.
  • Added background creation of a "library" of puzzles. This is created using the idle time of the computer, so it shouldn't slow down any other applications. When you request a new puzzle, the library is checked to see whether it contains a suitable one. If it doesn't, then the searching begins as in previous versions, but if it does, it's returned almost immediately. The background creation can be disabled from the options dialog if it causes any problems by slowing down other applications. This may be necessary on some older systems.
  • Added the ability to periodically check for updates online. This must first be enabled from the options dialog.
  • Fixed a bug that could prevent block/block and block/column/row interactions from being found when there were none of the relevant number in the grid.
  • Prevented an annoying, but otherwise innocuous, error message on startup if the PC has no default printer selected.
  • Auto pencil mark calculation is no longer unselected when the grid is cleared or the puzzle reset.
  • When looking for a hint, the currently allowed solving techniques are now tested before any disallowed techniques.
  • The correct solution and grade are now determined when pasting in a puzzle from an image.
  • When printing several puzzles at a time, it no longer calculates the pencil marks if the puzzle already contains any.
  • When printing a puzzle, the font used for printing the filename is now fixed at Arial size 12.
  • Changed the layout of the OCR Select Image Area dialog as the buttons could occasionally be positioned off-screen.
  • Added a timer. The timer value isn't saved with the puzzle though, so when opening a partially completed puzzle, the timer will restart at 00:00. The timer can by paused using the Pause key.
  • Added a menu option to automatically enter any hidden singles.
  • Added a sub-menu below File -> New to allow easy creation of a puzzle of a specific grade.

V2.7 2006-03-17

  • Added support for other languages. At present, there's Chinese, Czech, Dutch, French, Finnish and German. (Italian is available from our partner site www.sudokusol.it.) See the translation page for the downloads. If you'd like to translate Sudoku into your own language please contact me for details.
  • When a puzzle is first loaded or entered, it will warn if the puzzle has multiple or no solutions.
  • Can now optionally highlight incorrect numbers as well as invalid ones. (Incorrect numbers are numbers that do not match the solution, while invalid numbers are those that break the rule of Sudoku. Incorrect numbers are not highlighted if the puzzle has no or multiple solutions.)
  • Added a hint option. Press it once for a vague hint, again for more detail, and perhaps a third time for more detail still.
  • The puzzle grade is now optionally shown in the status bar.
  • Added the Select Technique form to allow for easier selection of several solving techniques.
  • Hidden singles can now be entered via a double-click (this function must first be enabled on the options form.)
  • Added short-cuts for the highlight and effects toolbar. Pressing the alt key along with a digit will highlight that digit, and pressing the control and alt keys along with a digit will show the effects for that digit.
  • The log viewer now remembers its size and position between runs.
  • Added an option to print up to six different puzzles on a single page.
  • It now saves and restores your preferred printer orientation.
  • Changed the order in which the swordfish and colouring techniques are applied. It is now swordfish before colouring.
  • Added an option to highlight cells with exactly two candidates.
  • Added an option to highlight numbers by filling the entire cell background.
  • Added an option to prevent the highlighting of big numbers.
  • For those who don't like the diagonal line used to show effects, I've added an option that will cause the entire cell to be coloured.
  • Added a menu option to automatically enter any naked singles.
  • A candidate elimination (or set of related eliminations) now counts as a move when single stepping. Previously, single stepping would make a many eliminations as necessary until it could place a big number.
  • The size of a big number has been reduced ever so slightly.
  • Pressing the Enter key on a selected cell has the same effect as double- clicking it and will complete naked and hidden singles as appropriate.
  • The highlights, effects and selected cell are no longer cleared when an auto-solve function is used.
  • After opening the internal log viewer, the focus is now returned to the main form.
  • Fixed a problem that could result in puzzles with multiple solutions when trial-and-error was an allowed technique.
  • When creating a new puzzle, the grid is now cleared before the puzzle is created.

V2.6 2005-12-13

  • Added a configuration option to control whether pencil marks are shown in a bold font or not.
  • Speeded up the identification of forcing chains.
  • Slightly modified the colouring solver to check for contradictions before double-exclusions.
  • Modified the grading function so that the grade form is visible while the puzzle is being graded. This makes it more obvious that something is happening if the puzzle takes some time to solve.
  • Corrected a bug that caused automatic pencil marks to not be calculated when opening a new puzzle.

V2.5 2005-12-09

  • Added ability to paste puzzle text containing candidate lists of the form
    (348)(346)(469)(7)(2)(1)(5)(389)(39)
    or
    (348)(346)(469)7215(389)(39)
    and other variations, that use any of the brackets (), {} or [] to surround the candidates and/or cell content.
  • Improved the forcing chain mechanism so that it now identifies both chains. For a very few puzzles, this can adversely affect the solving speed.
  • When copying the puzzle text to the clipboard, the format is now configurable.
  • the Control and Alt keys now allow the entering of a big number when the pencil-mark button is down, and vice versa. (Previously, the control key alone would allow entry of a pencil-mark when the big-number button was selected, but not the other way around.)
  • Disabled single-step and ten-step actions if the allowed solving techniques includes trial and error. This is because the board could be left in an inconsistent state after the allowed number of steps.
  • Modified the number selector so you can also select the cell colour.
  • Reduced the flicker of the number selector when double-clicking a cell with a single candidate.
  • Pencil marks are now shown in bold font.
  • Fixed a bug that could sometimes prevent a colouring chain being listed when two apparently separate chains are joined because they are mutually exclusive.
  • User colours are now saved to file, and so are loaded back in with the puzzle.
  • User colour operations are now added to the undo stack, meaning they can be undone.
  • When undoing a step, the selected cell remains selected.
  • Corrected a bug that could result in many cells being reported as forming a Swordfish. (The swordfish was correctly found, but incorrectly reported.)
  • Corrected a bug that could prevent XWings or swordfish from being found.

V2.4.1 2005-10-24

  • Modification to make the number selector background transparent for Windows 95, 98, ME and NT4.

V2.4 2005-10-17

  • Implemented optical character recognition (OCR). It's not perfect, but it does a reasonable job on many images. Simply open, or drag and drop an image file containing Sudoku puzzles, or you can also paste images from the clipboard. If the OCR finds a single puzzle, it will be imported. If the image contains several puzzles, you can select the one you want to import. It the OCR doesn't find a puzzle, you can help it by selecting the puzzle within the image - this is usually when the puzzle forms only a small part of the overall image. The OCR isn't perfect, so please check the imported puzzle against the original image.
  • Added a new number selector. For those who prefer to use the mouse, this is much slicker than the pop-up menus. Left click for a big number, and right- click for a pencil mark. For those that prefer the pop-up menu, the selector can be disabled from the Options dialog. And of course, the keyboard can still be used.
  • Added a menu option to save the puzzle as an image file - PNG, GIF, JPG or BMP formats are supported.
  • Added a menu option to copy the puzzle to the clipboard as an image.
  • The "effects" display now reflects the current state of the pencil marks, rather than the simple effects of numbers already present. This means the effects are updated as you eliminate cell candidates.
  • When opening a file with "auto-calculate pencil marks" enabled, the pencil marks are only calculated if none are already present. This prevents any manually adjusted pencil marks in the file from being overwritten by the auto-calculated ones.

V2.3 2005-09-26

  • Added the ability to manually colour cells, and the associated configuration options.
  • Sudoku no longer resets pencil-marks with each press of the Solve button. (But be aware that if you manually enter incorrect pencil-marks, you may prevent the solution from being found. If you suspect this is the case, simply delete all pencil marks before trying the solve again.)
  • When pasting a puzzle from the clipboard, all numbers are now assumed to be clues.
  • Moved the new puzzle options into the generic options dialog.
  • Enabled the "highlight" toolbar buttons even if there are none of that number in the grid, as this allows pencil marks to be highlighted.
  • Single stepping will now focus the cell it fills.
  • Corrected two static buttons when the internal log viewer window was resized.
  • Allowed the internal log viewer to stay open while the puzzle is solved.
  • Corrected a bug that could occasionally result in a puzzle being rated harder than it should.

V2.2 2005-08-20

  • Made the cell coordinate format configurable. You can choose from rYcX, cXrY, (X,Y), (Y,X) and A1-I9 formats.
  • Added simple colouring solving technique.
  • Reduced the time taken to generate new puzzles still further, and allow creation of puzzles with a range of difficulties.

V2.1 2005-08-02

  • Modified the terminology to reflect the terms now in more common usage. Changed "sole candidate" to "naked single", "unique candidate" to "hidden single", "disjoint subset" to "naked pair, triplet or quad", and "unique subset" to "hidden pair, triplet or quad".
  • Improved the swordfish algorithm so that it is recognised more frequently.
  • Reduced the time taken to generate new puzzles, but still room for further improvement.

V2.0 2005-07-28

  • Added the ability to create new puzzles based on the required solving techniques or degree of difficulty.
  • Added the ability to rate a puzzle.
  • Added the ability to rotate or reflect the entire puzzle, or substitute numbers.
  • Added swordfish solving technique.
  • Improved the X-Wing solving technique.

V1.9 2005-07-04

  • Added a new solving method "forcing chains".
  • Re-instated the trial-and-error method used when all others fail.
  • Added ability to count the number of solutions, and show you each one.

V1.8 2005-07-01

  • This version has been optimised to solve much faster.
  • It gives you control over which solving techniques are used.
  • better number highlighting
  • a few other bells and whistles have been added.

V1.7 2005-06-18

  • It now has full undo/redo capability
  • can optionally automatically update the pencil marks after entering numbers.

V1.6 2005-06-10

This version has more configuration options and a slightly improved user-interface.

V1.5 2005-05-24

Added the unique subset solving technique.

V1.4 2005-05-13

I'm afraid it's not all good news; from this version onwards, Sudoku is no longer free.

V1.3 2005-05-10

  • corrected a bug that could prevent pencil marks from being saved occasionally.
  • Some minor improvements to the user interface.

V1.2 2005-05-06

This version has some improvements that allow for easier entering of the puzzle clues.

V1.1 2005-04-26

This version addresses a minor bug that could prevent a solution being found in some circumstances.

V1.0 2005-03-19

First release.
What People Say

This is a wonderful program - the best I can find relating to sudoku ... Dare I say there is a bit of programming genius there.
Michael Wightman, UK
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