SudoCue News Archive


The search continues...

(Sunday December 19, 2021)
Years ago I started a search for Sudoku-X puzzles with 12 clues. Recently, the total count passed the 10000 mark. But now another search has started, this time for Windoku-X puzzles with 9 clues, early on already surpassing the Sudoku-X search with 13300 unique 9-clue puzzles.

Daily Nightmares are back in stock

(Saturday December 11, 2021)
The delivery of new Sudokus on this site has been a bit lacking the last 15 years or so, but now even the famous Daily Nightmare has a supply that will last several years. A page with an explanation of the requires codes will be added soon. Advanced solvers, such as the ones who taken on these puzzles, will figure it out soon enough.

Rejoyce, for there is a new contest of Clueless Explosions.

(Friday December 10, 2021)
Now starts a new series of daily Clueless Explosion puzzles. You can join the contest, or solve them at your own pace. The new free Clueless Helper can help you with this, and also gives you access to the last 60 Clueless Explosions in the archive.

From now on, there will be a daily Clueless contest puzzle.

(Thursday December 9, 2021)
A new Clueless Special will be waiting for you each day, and you can join the contest to see who can solve them the most and the fastest. The new Clueless Helper can help you with this, and also gives you access to the last 60 Clueless Specials in the archive.

As of this day, there will be a daily Samurai contest

(Thursday December 9, 2021)
I found a way to generate quality Samurai puzzles in large amounts, so the Samurai Contest will have a daily puzzle. A new version of the Clueless Helper will connect to this website to pick up the latest gattai puzzles, including the last Samurai.

A decade of Hanidoku puzzles in stock

(Saturday November 27, 2021)
Enjoy a new daily Hanidoku for the next 10 years, even if I cannot be present to maintain this poor website.

New One-Trick Ponies in Stock

(Saturday November 20, 2021)
Please enjoy a new daily One-Trick Pony for the next decade or so.

Stock of Daily Lite has been replenished until 2034.

(Saturday October 16, 2021)
Visit the Daily Lite page for a daily fix of fresh Sudokus in 4 difficulty grades. The online player can still be used, or you can copy the puzzle string and paste in into a suitable Sudoku program.

Fresh supply of Daily Sudoku-X puzzles

(Monday November 15, 2021)
Random generation of Sudoku-X usually produces a lot of extremely difficult puzzles. So I generated a lot and uploaded the ones which required only solving techniques like Naked and Hidden Subsets, Connected Pairs (a.k.a. Crossover), Basic Fish, Remote Pairs, BUG, Skyscraper, 2-String Kite, up to XY-Wing. You can find them for at least 10 years into the future at my X-File page.

Fresh supply of Daily Windoku puzzles

(Saturday November 13, 2021)
For the next 20 years, each single day there will be a new Windoku waiting for players on the Windoku page. Each of them requires solving techniques like Naked and Hidden Subsets, Connected Pairs (a.k.a. Crossover), Basic Fish, Remote Pairs, BUG, Skyscraper, 2-String Kite, up to XY-Wing.

DominoCue version 1.0

(Saturday December 1, 2007)
A new piece of sofware can be obtained at no cost from this website. Go to the DominoCue support page to learn about Domino puzzles and the program that can generate, solve and assist you in solving this intriguing puzzle format.

Samurai Rehab refresher program

(Thursday November 22, 2007)
The Samurai Rehab Center has now reopened with a refresher program for those who are still fighting their Samurai addiction. Many hidden pairs have been spotted in the center, but you can also enter the program as a single.

Website problems

(Wednesday November 14, 2007)
There was a problem with the website, with some strange results. Either the site did not load at all, or a different site was shown. Fortunately, the problem has been fixed now and no data has been lost as far as I can tell. My apologies for the inconvenience. - Ruud

SudoCue 3.1.0 - Service Pack 1

(Sunday August 26, 2007)
A few errors in the new release were fixed. You can now copy the RN and CN views as text to the clipboard. New menu option for adding convenient forum tags to copied text. Hotkeys for view selection.

SudoCue release 3.1.0

(Wednesday August 22, 2007)
A new release of SudoCue is available for download. Check the release notes for all the details. There are 2 new supported variants, new filter options and you can now transpose the grid in RN or CN view to check the techniques introduced by Denis Berthier.

Minimum Sudoku-X collection (with 12 clues)

(Monday July 23, 2007)
I've added a new page to this site, with information about 12-clues Sudoku-X puzzles, which I collected recently. The page explains the methods I used and also gives you access to the complete collection.

SudoCue version 3.0.0 released

(Sunday July 22, 2007)
It's been a while since I last released a new version of SudoCue. Although the program performs well, there were still a few issues that needed mending. I also worked on a canonicalization function that I wanted to add to the program. The new release is now available for download. Check the release notes for a list of changes. You can also download the program from this page.

So Soon: Texas Jigsaw Killer 32

(Wednesday July 18, 2007)
Now the activity on the TJK forum is on the increase, it is the responsibility of the webmaster to make sure these discussions do not die because of insufficient subjects. TJK 31 did not live up to expectations, so here is a real challenge. Please read the warning signs carefully (thanks Andrew Stuart) before you approach this Jigsaw Killer.

Black Friday

(Friday July 13, 2007)
The forum blackout has been fixed. To commemmorate this terrible event, I posted a fitting Taiken on the special page.

Forum down

(Friday July 13, 2007)
The forum is currently down because of a database error. I posted this error at my hosting provider. There is not much I can do at this moment to fix the error, but at a date like today something like this could happen...
I'll report back here when the problem has been fixed.

The Texas Jigsaw Killer lives!

(Friday July 6, 2007)
After a long period of silence, the Texas Jigsaw Killer has returned. It may not be as vicious as usual, so this would be a good starting opportunity for players who haven't tried this variant yet. The mixing of Killer and Jigsaw techniques will offer a fresh challenge.

Top 10000

(Monday June 18, 2007)
For the players who like a decent challenge and Sudoku program developers who want to test the strength of their solvers, I have assembled a Top 10000 of the puzzles which SudoCue can only solve by deploying its strongest weapons: Table Conflict and Table Verity. This collection replaces the Top 50000, which no longer meets this requirement.

Texas Jigsaw Killer 30 is here

(Thursday May 24, 2007)
There are several players enjoying the TJK in this site. Because they are handmade, it is difficult to release them at regular intervals. Number 30 is a tough puzzle with lots of LoL moves.

Samurai Rehab Center opened

(Sunday April 29, 2007)
A revolutionary detox program can help you get rid of your Samurai addiction in just 16 simple steps! Visit the Samurai Rehab Center for more information.

Queen’s Day Special

(Tuesday April 24, 2007)
A new puzzle format is waiting for you on the special page. 22 intertwined puzzles with many Clueless 3x3 boxes make it a good challenge, but it can be done with the usual suite of solving techniques. Meanwhile, there is another version of this puzzle on the user forum, named Catch 22. There is nothing funny about this puzzle. You probably need several AIC's spanning multiple sudokus to get somewhere.


(Sunday April 8, 2007)
A new puzzle format for this Easter, complete with X and Easter Bunnies. Enjoy!

Mystery Music Killer

(Wednesday April 4, 2007)
Get your CD collection and use it to figure out how to get all the cage sums in the right place. As a reward, you can solve an interesting Killer Sudoku. Check it out at the special page.

Clueless-Sumo-X special

(Saturday March 17, 2007)
The special page has a new addition. This Clueless-Sumo-X has 14 overlapping puzzles, one of them broken into 9 pieces according to the Clueless format. All puzzles require digits 1 through 9 in both diagonals. Although it is smaller than the Clueless Shaolin, it has a pretty tough solving path, including several X-Wings.

Daily Jigsaw Sudoku starts Monday, March 12

(Sunday March 11, 2007)
Requested by several forum members, a new daily puzzle will be available on The Daily Jigsaw starts at a moderate level on Monday and the difficulty level will increase till Sunday, when the real challenges are waiting for you. An archive is in the making. Make sure you understand the Law of Leftovers. You’ll need it... again and again and again...

New menus

(Friday February 23, 2007)
If you do not notice something different on this website, you probably have disabled Javascript in your browser. Others will notice the new menu bar, which replaces the navigation bar. The new menu provides access to every page on the SudoCue website. If you encounter any problems, blame it on the fact that I’m a lousy Javascript programmer. The menu seems to work fine with the major browsers.

The Clueless Special competition

(Sunday February 18, 2007)
Will Alain Garnier join Pete at the top of the list next week? Will Gemma give us a solid performance for the next 4 weeks and reach the gold medal position? What country will take the lead next? Join the Clueless Special competition and be part of the action.

Valentine Special

(Wednesday February 14, 2007)
Ladies only... I'm clueless as to who put it there...

Daily Lite page improved

(Tuesday February 13, 2007)
The Daily Lite page offers daily Sudokus in 4 grades for the beginner to moderate player. It attracts a lot of visitors, so I have improved the page to please all these visitors. A Marks button automatically calculates all remaining candidates. The grid has been enlarged for better readability. Filter buttons on top of the grid highlight remaining candidates for a digit. You need to enable Javascript in your browser to use all these sophisticated tools.

Chill Down Special

(Tuesday February 6, 2007)
Because the winter season can be cold and stressful, I made a nice puzzle to relax a little. Do not worry if you cannot finish it this season. There’s always another winter coming. You can find this puzzle on the SudoCue Special page. Turn up that stove and enjoy this puzzle.

Where did those ads go?

(Wednesday January 31, 2007)
Now that my PayPal account is back in action, several people have made a generous donation. As a token of gratitude, I have removed all Google ads from this site. A warm “thank you” to those who have made this possible.

New Killer-X special

(Saturday January 27, 2007)
If you fancy Killer-X puzzles, check the special page for the fourth special puzzle of this variant. Diagonal connections make is a very tricky puzzle!

Clueless and Samurai Helper, release 1.1

(Monday January 22, 2007)
Just in time for Samurai number 10, you can download and install the latest Clueless Helper, which also allows you to play the Samurai puzzles posted on this website. Go to the download page to get this version. The on-site documentation has also been updated with the new release info.

Sumo X on the User Forum

(Sunday January 21, 2007)
A brand new Sumo-X puzzle is waiting for you on the User Forum. Many regular players enjoy these puzzles. Friendly responses may encourage me to post a few more...

New website look

(Friday January 19, 2007)
You surely noticed that this website has undergone some cosmetic changes. You may have to refresh the page in your browser to update all images and the style sheet.

Another addition is the long-expected archive for the One-Trick Ponies. Also, the RSS feed is now automatically detected by most browsers, including IE7.

Clueless Explosion competition

(Wednesday January 17, 2007)
Thursday January 18, a third competition will launch on this site. Requested by many players and supported by a poll on the forum, the Clueless Explosion will be the 3rd puzzle format for which you can submit your solution. No speed bonus, so you can spend a whole week solving it. Maybe a triathlon list will be the next request. I will keep an eye on the forum. Enjoy the competition. First competition puzzle will be released at High Noon GMT next Thursday.

Killer-X special number 3

(Saturday December 16, 2006)
I know there are many players who love this variant. These puzzles are difficult, but very rewarding when you manage to solve them. The latest addition can be found at the special page.

Michael Mepham

(Friday December 15, 2006)
I was shocked and saddened when I heard that Michael Mepham died yesterday. He played an important role in popularizing Sudoku and many of its variants, as a puzzle maker, but also as the author of several great Sudoku books and articles. Many Sudoku players have found their way to his website and came to appreciate his “diabolical” and “extreme” puzzles. As a moderator on his forum, I had regular contact with Mike and considered him one of my friends. My thoughts are with his wife Brenda and his children.

Daily Nightmare number 365

(Monday December 11, 2006)
Tuesday December 12 features Daily Nightmare number 365, completing a year of terror in Sudokuland. This milestone puzzle is the “Mother of all Nightmares”, requiring 41 advanced solving steps in SudoCue. I hope you will enjoy this very special Sudoku puzzle.

SumoCue version 1.3.0 released

(Sunday December 10, 2006)
Although this program does not require as much maintenance as SudoCue, a new release was long overdue. In this release, the program will detect Law of Leftovers and Pattern eliminations. Jigsaw players will be glad to see the new dialog that allows you to select a predefined Jigsaw pattern. All patterns used at are present. Also, a new menu option allows you to copy the candidates in a format recognized by SudoCue. Proceed to the download page to obtain this new version.

SudoCue version 2.2 released

(Friday December 8, 2006)
I finally found the time to finalize a new release of SudoCue. All the information you need is in the release notes, but advanced players will certainly like the newly supported solving techniques and variant addicts have also a number of new toys to play with.

A Windmill from Holland

(Tuesday November 28, 2006)
Please have a look at the special page for my latest invention, the Kazaguruma (Windmill). A very interesting overlapping puzzle that allows you to perform the twin-nonets technique, which is not possible in those boring Samurai puzzles. - Did I really say “boring”?

Samurai Contest starts Tuesday November 21

(Sunday November 19, 2006)
Get into shape, quickly. This is your chance to appear at the top of a competition list. Next Tuesday, November 21, at 00:00 GMT the first Internet Samurai Contest starts here at Every week a new Samurai Sudoku for you to solve. Submit your solution within a week and become a listed person.

One-Trick Ponies

(Saturday November 18, 2006)
For some players, the Daily Nightmare is too much of a challenge. It is true that they have grown tougher, as I expected you to improve your solving skills in time. This puts new players at a distance and they may not be able to catch up. For those players, and every other Sudoku addict, there is the One-Trick Pony, a carefully selected Sudoku that requires only a single advanced solving step. Besides that One-Trick, they are very pleasant toughies. Enjoy!

My First Samurai

(Friday November 17, 2006)
It had to happen sometime. The special this week is a Samurai. Enjoy the puzzle and let me know if you like it.
I also posted the decompressed puzzle that I introduced last week. It is no Nightmare, but nevertheless an interesting Sudoku.

Mystery Decompression Sudoku

(Friday November 10, 2006)
Enjoy the new special. It is a standard Sudoku that is efficiently compressed into a short string. I sort of forgot how it was compressed, but I seem to remember that is was symmetrical. Can you help me retrieve the original Sudoku? And while you're at it, try to solve that Sudoku for me, will you, please?

Sudopedia blossoming

(Thursday November 9, 2006)
There has been a tremendous amount of writing done in Sudopedia, the free Sudoku Wiki. The list of Sudoku terms exceeds my own glossary, because it also defines terms used in highly advanced solving techniques, which are not (yet) explained in the solving guide. There is stil work to be done.
(read more...)

New Killer-X Special

(Friday October 27, 2006)
A guy named Ed asked me to publish another Killer-X puzzle. You can find it on the special page. A very hard puzzle, but solvable without guessing. I'm looking forward to read your walkthroughs.

I also posted a hint for the Mystery Letter Sudoku, in case you are still struggling with it.

Sukaku page added

(Friday October 27, 2006)
A new Sukaku page is added to this website. You can find it in the navigation bar, just above the donation info. The page introduces you to the new Sukaku format, where no given numbers are present, but only a pencilmark grid. I also keep track of records on this page.

SudoCue 2.1 ready for beta testing

(Tuesday October 24, 2006)
If you like to try new things, download the beta version 2.1 from the download page. Maybe you should read the release notes first.
I have done a lot of testing, but the program is very complex, so I am unable to test every possible contingency. Please report errors (if there are any) quickly. All known bugs were solved in this version.

SudoCue version released

(Sunday October 15, 2006)
This release fixes the errors that were introduced in the "paste" function. It should no longer be a problem to paste the Sukaku puzzle from the special page into the program. Due to an error on my webserver, I could not record this new version yet. Until the webhost has fixed the problem, the version check will report an error.

An extra Special: Mystery Letter Sudoku

(Friday October 13, 2006)
This is a nice puzzle experience. There is a way to convert letters into numbers. I am not the one who is gonna tell you how to do this. That is part of the puzzle. Be creative and you will find a way...

Another first on the Special page: Sukaku

(Thursday October 12, 2006)
I have created a Sudoku puzzle that has no clues. Since I already have used the name Clueless, I have named it Sukaku, an abbreviation for the Japanese term “the numbers are hidden”, which seems to be so. You have to solve the puzzle starting with the pencilmark grid that you see. The normal Sudoku rule is used.

Mr Fixit came by

(Tuesday October 10, 2006)
A couple of reported bugs in SudoCue were repaired by Mr. Fixit. Version is available for download.

A Special Killer-X

(Thursday October 5, 2006)
Check the Sudoku Special page for a Killer-X with a stunning cage pattern. It has a very interesting solving path, where 3 is the magic number...

Solving Guide update

(Monday October 2, 2006)
I have replaced some images in the solving guide by better examples using SudoCue version 2 candidate highlights. The guide now also has puzzle strings which you can copy and paste into SudoCue or your preferred Sudoku program. If you have recently visited the guide, you may need to refresh the page to replace the old images in your browser cache.

New release of SudoCue

(Sunday October 1, 2006)
A few more fixes and improvements for version 2. For more info, read the release notes.

A new Crossword Killer

(Thursday September 28, 2006)
I received encouraging feedback on my first Crossword Killer, so I decided to create another one. If you need a hint for the 9-letter word: Look at yourself in the mirror trying to solve this puzzle. The puzzle can be found on the specials page.

The Learning Curve Collection

(Wednesday September 27, 2006)
Are you bored of those easy Sudokus in the local newspaper, but not ready for the extreme challenges posted on this website? There is a remedy nearby: The Learning Curve collection.
This collection contains puzzles which gradually increase in difficulty, either because there are more techniques required or because the next step is harder to find.
(read more...)

SudoCue version 2.0.0 released

(Monday September 25, 2006)
Hurry to the release notes to see why you should install this great new version of SudoCue. The boring appearance can be replaced with several different styles. Hints are greatly improved with candidate and group highlighting. A very advanced solving technique, 3D Medusa coloring, has been added to the solver.

Clueless Special schedule changed

(Saturday September 16, 2006)
This announcement has already been made on the forum. As of Saturday September 16, the Clueless Special will be released at 10:00 AM GMT. Players have requested this change, so they can use the weekend to earn the extra point for submission within the first 24 hours. Who am I to refuse it?

My First Crossword Killer

(Friday September 15, 2006)
On the Sudoku Special page, you can find the first Crossword Killer I made. This puzzle tests both your Math and Language skills. You can use the latest version of SumoCue to play this variant.

Two free Clueless demonstration puzzles available

(Wednesday September 13, 2006)
You can now test the new Clueless Helper with 2 fine Clueless puzzles, which you can find on the download page. Right-click the links and choose “Save target as...” to save the file on your computer. After that, you can open them with your Clueless Helper.

Clueless Helper released

(Tuesday September 12, 2006)
I have been working on this program for more than a week, which may explain why I have not been so quick in responding to all questions. The Clueless Helper is designed to make it easier to solve the Clueless Specials and Explosions published on this site. You still need to solve the puzzles by yourself, but the program has an excellent set of tools to help you with it. You can try the program for 30 days, or buy it for 5 US Dollars. A real bargain.

Release of SudoCue

(Saturday September 9, 2006)
I implemented a few improvements suggested by regular users. To save some time eliminating multiple candidates, you can select multiple cells. Print puzzles partially completed or even with pencilmarks. Large print option for the players having trouble reading the small print. Skip all single moves with a single key (pun intended). Some minor fixes.

Try the new Sudoku Special

(Friday September 8, 2006)
After the successful introduction of the Clueless Special, you will now find a new Sudoku variant on this new page. The first special is a - never seen before - 12x12 Sudoku DG. Check out this site from time to time if you like new Sudoku surprises.

SudoCue’s Most Wanted

(Thursday September 7, 2006)
I replaced the extreme tracker with my own tracking system, so we can do more with the results. With a large website like this, it is sometimes hard to know where to start looking for the good stuff. I try to make sure everything is equally interesting, but some pages are obviously more popular than others. If you like to follow the crowd, try the new Most Wanted list, that shows the 20 most popular pages on this site, with a visit count for the last 24 hours.
(read more...)

New Killer Sudoku Links page added

(Tuesday September 5, 2006)
People who occupy themselves with classic Sudoku and those interested in Killer Sudoku live in different worlds. There are only a few exceptions. I am one of them. I could not find any good collections of Killer Sudoku website links. Today, that gap has been filled. I moved the killer links from my Sudoku Links page to a brand new Killer Links page, and added several new links to interesting sites. Just contact me if you think I missed an essential site.

“Guess What?” theme week

(Monday September 4, 2006)
Theme weeks are fun. This week is even more fun. Starting September 5, a mystery theme week will be running on If you know what the theme for the week is, tell us on the Daily Nightmare forum. Do not start guessing too soon. You need a couple of Nightmares to figure out what the theme might be.
(read more...)

SumoCue version 1.2.0 released

(Sunday September 3, 2006)
The long awaited new release of SumoCue is finally here. Go and get it from the download page if you cannot wait any longer. The solver has learned a few new tricks, a new popup option will make your life a lot easier and you can now do crossword killers with the program.

New Theme week: Almost Locked Sets

(Monday August 28, 2006)
Now that the holidays are over, it’s time to get back to work. The Daily Nightmares will teach you what hard work is. Starting Tuesday, all week long you will face a very tough Nightmare that contains one or several ALS steps in the solving path. The only way you can cheat your way around these steps is to guess (wash your mouth, Ruud!) or use several Forcing Chains. You might also find the occasional Empty Rectangle.

SudoCue additional version

(Sunday August 27, 2006)
I’m planning to leave SudoCue at this level for a while, and only do small fixes, so I can spend my precious time on the next release of SumoCue. The formal release 1.5.1 did not have any new solving techniques, but they were ready to be released. I needed to do a few more tests. Now they are ready. “Empty Rectangles” is a technique that many solvers can use, but “Almost Locked Sets - XZ rule” is a very powerful addition.
(read more...)

SudoCue version 1.5.1 released

(Friday August 25, 2006)
A minor release with a few fixes and additions. People who compete in the daily sudoku competition at Mike Mepham’s site may find a pleasant surprise in the menu. Undo also operates on pencilmarks. The optimizer itself has been subject to optimization.

Daily X-Files for you to solve

(Monday August 14, 2006)
I'm afraid Scully and Mulder won't be able to help you with these X-Files, so you're pretty much on your own, unless you decide to partner up with SudoCue.
Each day you are given a new X-File to solve. It contains 2 puzzles in Sudoku-X format, an X-R-Size and an X-Treme puzzle. Try to solve them without embarrassing the Bureau...

Glossary revised

(Sunday August 13, 2006)
After the solving guide has gone through a series of revisions, it was time to refresh the glossary too. The page has a more compact style, with many internal links, and updated links to the solving guide. Commonly used terms have a tooltip-like text. Just hang around with your mouse for a while. Many new terms and solving techniques have been added.

String of Pearls week started

(Friday August 11, 2006)
Starting today, there are 7 Pearls in our Daily Nightmare series. These were found in the same waters where we did our little fishing expedition a little while ago. A Pearl, according to Gurth Bruins, is an interesting sudoku that has no free singles to start with. Together with the symmetry, this gives these puzzles a higher aesthetic value. I fully agree with his point of view, so here they are.

Killer Configuration Tool added

(Wednesday August 9, 2006)
A useful tool for players of Killer Sudoku and Kakuro. Enter the sum, select a size (you can also choose several size combinations for outie calculations) and choose which digits are required and/or forbidden. The tool will show you all possible digit combinations.
(read more...)

Variations galore! SudoCue 1.5.0 officially released.

(Saturday August 5, 2006)
Check the release notes for what's new in this marvelous new release. SudoCue is now the only program that generates and helps you solve the most popular Sudoku variants: Sudoku-X, Windoku (NRC) and Disjoint Groups. It is also the only program that can handle these variations with all the firepower of an advanced sudoku solver. If there are 8-fold crossovers in a Sudoku-X, this solver will find them.
(read more...)

SudoCue User Guide online

(Friday August 4, 2006)
The documentation provided with the SudoCue program has been lagging behind with all the new and exciting developments. Many features of the program remained undocumented and you had guess how it works. Since most Sudoku players hate guessing, this has not been good for the reputation of the program. I have spent a serious amount of time on rewriting the manual and decided to publish it here on the site. The inline documentation will no longer be included in the next release.
(read more...)

Daily Windoku available on this site

(Tuesday August 1, 2006)
I have done a lot of research into the Windoku format, with 4 window panes that also require digits 1 through 9. This variant is also known as NRC sudoku. I also make these puzzles for magazines, so I wanted to fine tune my rating system for this variant. Having completed the code, I can now generate Windokus in any grade. The best are posted daily, complete with an archive and print option.
(read more...)

Superiors collection

(Friday July 28, 2006)
Check the download page for a collection of 160 Superior sudokus.

SudoCue Release 1.4.1

(Thursday July 27, 2006)
New releases are coming like bullets from a machine gun. This release does a little damage repair for the bugs that were discovered in the last release. A new technique is spotted by the solver: XY-Chains. This may have an impact on future Nightmares. Many improvements have been made to the much debated user interface. I hope you like them.
(read more...)

Almost Nightmares

(Monday July 24, 2006)
The puzzle collections that I publish are very popular. Time to add a new collection to the download page. This collection contains 400 sudokus that just did not make it to become a Daily Nightmare, but they are too good to throw in the bin.
(read more...)

SudoCue release 1.4.0

(Saturday July 22, 2006)
I have been rewriting major parts of the program to complete this version. In the old architecture, it became increasingly more difficult to add new solving techniques. The new architecture makes it possible to add new techniques in minutes, with the user in full control over its use and place in the hierarchy. Many simple tricks have been added. The User Interface has also seen some improvements.
(read more...)

Fishing Expedition July 16 through 22

(Sunday July 16, 2006)
I hope you have been able to catch a few bugs last week, because it was very difficult to follow the intended solving path. If you didn't, you can always use something else as bait, because the Fishing Expedition has started.
(read more...)

Clueless Explosion, a new variant

(Saturday July 15, 2006)
A slight change of the Clueless concept has now been added to, the only website that brings you these puzzles. The 10th sudoku is now made from all the cells that lie in the center of a 3x3 box. It looks like a regular Clueless where the blue boxes have exploded.
(read more...)

Check your Clueless Special submissions

(Friday July 14, 2006)
A new page, as promised, allows you to see your performance compared to the other competitors in the Clueless Special competition. There are not many competitors yet, but you are invited to join the competition.

SudoCue release 1.3.1

(Wednesday July 12, 2006)
A new release of SudoCue is available for download. The user interface has been improved and the generator has undergone some important changes. Quite a few user requests have been incorporated in this new release. When no problems arise, this release will be official in 2 weeks. Until then, the previous release is available for recovery.

July 8 until 14 is BUG week!

(Saturday July 8, 2006)
It is inevitable that the warm weather of the last weeks has an effect on bugs. They're everywhere. Even in the Daily Nightmares. All week long.
(read more...)

SumoCue release 1.1.6

(Thursday July 6, 2006)
There were a few problems with the automatic switch to jigsaw mode that I fixed. If you're not using SumoCue to manually enter Jigsaws or Jigsaw killers, you do not need to upgrade to this version.

Solving Guide “under construction”

(Thursday July 6, 2006)
I have rewritten large parts of the sudoku solving guide on this site. The guide also has a new set of images, and many new topics have been added, like hidden subsets, X-Wings and Swordfish. I'm currently writing more about advanced techniques. Feedback is appreciated.

Advanced warning: Daily Nightmare 7-7

(Tuesday July 4, 2006)
Prepare some time in your agenda for the Daily Nightmare of 7-7. There are ample opportunities to use the best solving techniques you have available.
(read more...)

4 more Daily Sudokus

(Tuesday July 4, 2006)
Amazing how fast a website can expand. On the Daily Lite Sudoku page, you can play 4 different levels of sudoku each day. A javascript user interface allows you to play these puzzles online, with pencilmarks.
(read more...)

News archive started

(Monday July 3, 2006)
The news items on this site are now automatically archived. This archive allows you to read news items, which I no longer consider news and have been dropped from this main page.
(read more...)

Clueless Special Guide

(Monday July 3, 2006)
To introduce you to the Clueless Special format, a Clueless Special Guide has been added to This page explains how the format works, how best to solve the puzzles and it contains an easy starter to get your feet wet.

HaniDoku Website

(Thursday June 29, 2006)
A new puzzle format has been invented (or reinvented, who knows?) I named it HaniDoku and you can find more information about this format on my new website, The honeycomb shape with lines in 3 directions of different length and the absence of boxes bring some interesting twists to this variant. One thing is certain, you can't keep your head straight when solving a HaniDoku!
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Clueless Special competition

(Friday June 23, 2006)
The Clueless Special has turned into a competition. I received a lot of e-mails with solutions to the Clueless Special. From now on, you can submit your solution on the Clueless Special page. Shortly, a winners list will be shown on the site. Are you up to this challenge? Then sharpen your pencils.

Killer Solving Guide

(Monday June 19, 2006)
A Killer Solving Guide has been added to the site. It explains solving techniques especially for Killer Sudokus. You can practice these techniques with sample killers and use them in th solving strategy you learn on this page. You can solve most Killer Sudokus when you follow these guidelines.

End of Pop age

(Thursday June 15, 2006)
No more popups and pupunders. We punish Webstats4U for their aggressive popping policies. After counting 42464 pageviews they're gone.

SumoCue release 1.1.5

(Thursday June 15, 2006)
Our SumoCue program has quickly become a very popular choice for solving Killers, Jigsaw sudokus and Jigsaw Killers. The current version 1.1.5 supports jigsaws, toroidal nonets and cages, killer-X, zero-killers and diagonal cage connections. Puzzles can now be printed.
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SudoCue release 1.3.0

(Tuesday June 13, 2006)
Version 1.3.0 of SudoCue is now available on general release. Check the release notes to see the changes in this version. No fish escapes the net. When you are interested in Braiding or Traveling Pairs, you can use the new analyzer windows for this technique. The random generator and optimizer have been improved. No hung system any more, and check out all the new symmetry options.

Texas Jigsaw Killer

(Thursday June 8, 2006)
The Texas Jigsaw Killer may sound like the name of an old horror movie, but in reality it is the latest puzzle that you can find on this site. These puzzles cannot be found elsewhere. And you can use SumoCue to solve it.

Weekly Assassin

(Friday June 2, 2006)
A Weekly Assassin is the latest addition to this enigmatic site. This is a killer sudoku that requires the best of your solving skills. What else would you expect from us?

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