SumoCue - Introduction and Guide



SumoCue is a freeware helper and solver for Killer and Jigsaw Sudokus. If you like the Killer variant, but you're not really into all those calculations, you may find SumoCue a very useful tool. It keeps track of cage sums and digit combinations that are allowed. Candidates are maintained by the program, but you can always intervene. It is one of the few programs that allows you to enter and solve Jigsaw Killer Sudokus.

Release 1.3.0 has additional support for the Jigsaw variant. The program can give you Law of Leftovers hints and can also detect any single digit elimination through a pattern check. For those who play the Jisaw competition at Mike Mepham's website, a new dialog allows you to select one of the predefined jigsaw patterns. A new menu option allows you to copy the candidate grid without the cage sums, so you can paste it in a regular Sudoku program, such as SudoCue.

Release 1.2.0 supports Crossword Killers.
Thanks to Nate Dorward, several Killer solving techniques have been improved.
You can now also manually disable/enable cage combinations.
Right-click a cell, an a popup menu with useful options appears. When a cell has the same number of candidates as its cage, you can lock these digits in this cage with a single click from this context menu.
The documentation lags a little behind, but here are the additional tools for Crossword Killers:

  • In a Crossword Killer, some cells are not covered by a cage. Each group of 2 or more adjacent cells without a cage in each row or column must contain a valid word. A table shows which letter replaces each digit.
  • Enable crossword mode with a new Crossword Killer options dialog.
  • Enter the digit-to-letter mapping
  • Manually enter all possible words, or better, use the Internet Anagram Server to collect them.
  • Press L to activate Letter-markup. All big and small numbers are replaced by letters where cages are missing.
  • Press Shift+Letter to enter a letter into a cell
  • The solver will use the list of possible words to give additional hints

Release 1.1.7 did have a first draft of the Crossword additions. It was not an official release.

Release 1.1.6 fixed a bug that did not switch to jigsaw mode in al cage drawing tools. Some helptext has also been added to clarify the design tools.

Release 1.1.5 has (hopefully) the innie-outie difference bug fixed. Another bug that left a part of the cage when deleting it has also been repaired. You can now print the puzzle, optionally with pencilmarks as they are visible on screen. The sum tool now has an auto-compare mode. The program will automatically show the difference to the nearest multiple of 45. When cages are selected for summing, the selected cages have more recognizable colors.

Release 1.1.4 has additional support for regular jigsaw sudokus. After drawing the jigsaw nonets and the switch to jigsaw mode, simply place the clues by entering the digits. This will create cages of size 1 in setup mode, which will be hidden when you switch to play mode. A tool for recognition of killer pairs has been added. This technique is also implemented in the solver. The DLX solver can solve any variation now. A bug in the innie-outie difference calculation has been fixed.

Setup Mode

When you start SumoCue, you will see an empty grid. Type the cage sums with the focus on one of the caged cells and use Control+Arrow keys to expand the cage. You can use the number keys on top of the keyboard or on the number pad to enter cage sums. The sum will automatically appear in the top-left cell of the cage, regardless of the currently selected cell. It is not possible to enter a cage sum greater than 45. If you made a mistake, use backspace to remove the last digit. If you made a mistake in drawing the cage, press Delete to remove the cage. To draw large cages quickly, click a cell to select it, and then click a second cell while holding down the Control key. This will add the rectangle between these 2 cells to the cage that contains the first cell. When finished, use the menu to Save the puzzle and you can start solving it.

For Jigsaw Killers, first draw the jigsaw nonets. The program will ask you to switch to Jigsaw mode once you have drawn 9 cages of 9 cells each. The standard 3x3 boxes will be replaced by the nonet borders and you can continue to draw the cages.

As of version 1.1.3, the program also supports regular Jigsaw Sudokus. Draw cages in the shape of the Jigsaw nonets first. Confirm the switch to Jigsaw mode. Now enter the givens. The program will create cages of size 1 as long as you are in design mode. When you select the Play or Save menu options, the program switches to Play mode. As long as you did not draw cages containing multiple cells, the program will stay in regular jigsaw mode. The solver can help with the basic solving techniques, but does not recognize advanced jigsaw techniques yet. The DLX solver can solve jigsaws and verify that there is only one solution.

I stead of entering the cage data manually, you can also open a previously saved puzzle. The SumoCue format uses files with a '.sum' extension. However, the program can also open files containing regular killers, saved with Perfect Sudoku by DJApe.

To design your own killers, Set the diagonal option and draw nonets if you want to make a jigsaw killer. Now paste an existing solution in the program, or press F12 to let the program generate one. Now draw the cages. When doubles appear in cages, they are shown in red. If you want another solution, press F12 with the cages already drawn. The sums will be recalculated. Switch to play mode to test the puzzle. Post your best puzzles on our user forum. DJApe also has a forum the allows you to publish your own killers.

A third alternative is to paste a string containing a puzzle in SumoCue or Perfect Sudoku format. The latter is the most popular format in which Killer Sudokus are posted on forums, but it cannot define jigsaw killers. The program will ignore blanks and line breaks when processing a pasted string. The PS string should start with '3x3::k:'.

Play Mode

An option setting allows you to turn off the 3x3 box constraint. If you wish to play a game without this constraint, turning this option off must be done before any value is entered into the grid. The program automatically removes candidates following the row, column and box constraints.

Use the number keys to place digits. Use Backspace or Delete to remove an entry. The program does not automatically restore candidates when you remove a digit. If you made an error, you can always Restart the puzzle.

There are 5 tools available in play mode. Here is a short summary:
Filter - Shows a green background for all cells that accept a selected digit.
Markup - Shows the available candidates in small numbers.
Configuration - Shows possible digit congigurations for current cage.
Pairs - Shows possible killer pairs in cages, and their effective houses.
Sum - Performs quick calculations for selected cages and cells.

The Filter Tool

Press 'F' to activate or deactivate the Filter tool. You can also select the menu option. When the filter tool is active, a small buttonbar is visible below the grid, where you can select the digit to be filtered. To navigate quickly through the filter digits, use the comma and point keys, with the '<' and '>' showing the direction in which to navigate. SudoCue users already know the use of these keys.

When the filter tool is active, you can toggle the filtered candidate for the selected cell with the space bar. The same key is used in SudoCue.

The Markup Tool

Press 'M' to activate or deactivate the Markup tool. You can also select the menu option. With the Markup tool active, you will see all available candidates as small numbers in each cell. This helps you spot locked pairs and other patterns in the grid. A series of checkboxes below the grid allows you to toggle any candidate for the selected cell.

The Filter and Markup tools can be active simultaneously. Any candidate change made with one tool is also shown in the other tool.

The Configuration Tool

Press 'X' to activate or deactivate the Configuration tool. You can also select the menu option. The Configuration tool shows the possible digit configurations for the cage containing the selected cell. Configurations are only shown for the remaining empty cells. When a cage is completely filled or there is only one empty cell left, the Configuration tool does not appear as there is only one configuration left.

Configurations which require digits no longer found as candidates are shown dimmed in the list. This will help you determine which other candidates can be eliminated. The Configuration tool only looks at the total set of candidates within the cage. You still have to work out which combinations actually fit into the cells.

The Pairs Tool

Press 'P' to activate or deactivate the Pairs tool. You can also select the menu option. The Pairs tool shows the candidate pairs for the cage containing the selected cell. There can be multiple pairs in a single cage. The program forms a pair between a digit and another digit that is used whenever the first digit is not used. Below the list of pairs, you will see which houses (rows, columns or nonets) are affected by these pairs.

The Sum Tool

To activate the Sum tool, just select one of the menu options in the Sum menu. To deactivate the tool, press 'Z' (zero) to clear the sum or use the Clear Sum menu option. Many keyboard shortcuts are now available.

To find 'innies' select all cages in a row, column or box without those partially outside the unit. For 'outies', select all cages including those that protrude partially from the unit. There are menu options that automatically select all cages in a row, column or box. These can be used multiple times if you need to check multiple units. Use auto compare or select one of the compare values to have the program calculate the exact difference between the summed cages and a multiple of 45. The sum and the difference are shown on the statusbar.

Shortcut keys are '+' and '-' to add or remove the cage containing the selected cell, and 'A' and 'S' to add or subtract the current cell. Availability of menu options depends on placing of digits and whether the cage is selected. Slight color changes (a little brighter) will show you the selected cages and cells for the Sum tool.

Other features

Undo and Redo are available and affect both placed digits and candidate changes. When you made a mistake, use Undo to erase it. Use Redo to make the same mistake again, or redo the action that was not a mistake after all.

Press F8 for a hint. The hint will show on the status bar. Press F11 to step towards the solution. These steps can be Undone. For hints and steps, the solver always checks the current state of the puzzle. Use the Solve menu item to call the built-in backtracking solver. No hints are given, but the puzzle is validated and solved.

A short inline help screen is now available.


When you solved the puzzle, all tools are turned off and the background color changes. Use the menu to copy the solution in a string with 81 numbers. Some websites with Killer challenges do accept the solution in this format.

Download and installation

Download SumoCue, version 1.3.0

Use the Windows installer to install the program. If you do not have the .Net Framework installed, you will be redirected to a download site by Microsoft. You can choose the redistributable framework package version 2.0 for x86 processors, if you have a normal PC.

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