Solver App for Android and iPhone
Strategies for Number Puzzles of all kinds
Latest Apps
Page:2020 2019 2018 2017 2016 :1 2 3 4 :2015 2014 2013 2012 2011 2010 2009 2008 2007 2006

Feedback and Questions

I've received a lot of interesting comments and questions from Sudoku fans over the last few years and this page is where I try to answer them. Please feel free to drop me a note on the side of the page or try the Facebook comment box. Or you can email me directly at .

Post a Comment or Question here...
Your Name or 'Handle'

Part of the World you're from

Email Address (optional) so I can reply directly if necessary (it will not be displayed here)

Any Sudoku you want to publish here for easy loading into the solver - 81 characters, use '.' or '0' for unknowns.

public - comment/question will be added to feedback column
private - email comment/question directly to Andrew Stuart, don't display here

Comment, question or feedback:

Enter these letters
Please enter the
letters you see:
Many thanks to all the people who have helped improve the solvers and strategies with their feedback!

Friday 12-Feb-2016

... by: S K JAIN, INDIA

I have written a sudoku solver software that can solve the sudoku puzzles from pure logic. I have implemented most of the widely used sudoku techniques (including the very advanced techniques). It can solve the hardest and toughest sudoku from pure logic (with the help of Adrianne's thread technique when the sudoku is stuck and all other techniques fail). You can download the source code for free for the sudoku software for free from my website. The website is :

Andrew Stuart writes (18-Feb-2016):

Well done, programming a solver is the most satisfying endeavour. I've really enjoyed that aspect of it.
You say "Adrianne's Thread". Do you mean "Ariadne's Thread"?
I remember that strategy when Michael Mepham first published his Sudokus in 2005. It was the "all logic fails me" strategy. Since then the community has expanded the logic space to we need to resort to it less, but I class it as a "trial and error" strategy and therefore outside pattern based logic.

Thursday 14-Jan-2016

... by: nono, france

Hi Andrew,

a good new year to you and also for all players here.

will it perhaps be possible to see, for a same strategy, that the solver shows all the possibilities for a sudoku before going further ?

Andrew Stuart writes (15-Jan-2016):

If you mean given strategy X cycle through all the eliminations that are possible with that strategy at that point, then yes,
thatís something I'd like to do. It will greatly complicate the solver user interface which is why I've hesitated.

I do have complex heuristics and rules to try and return the "best" in each strategy but there is still a small bias to top-left bottom right as most searches scan that way.

Tuesday 12-Jan-2016

... by: Andi, Florida

I love doing the sudoku puzzle every day! It's very relaxing! It's been the same puzzle for about 5 days....what's up?

Andrew Stuart writes (15-Jan-2016):

I have this problem for KenKen (run out of puzzles) but I didn't think I was low on Sudoku. What page or app are you using?

Tuesday 12-Jan-2016

... by: KenKenFan, USA

I'm no longer getting a new Daily KenKen when I click on that puzzle. I've been getting the same one for over a week. I tried closing the site and reopening, but it still happens.

Andrew Stuart writes (15-Jan-2016):

Yeah, I've run out of puzzles and the generator is not working - since I last ran it I've made too many changes elsewhere in the code. Am trying to fix it and get some more puzzles up!

Thursday 7-Jan-2016

... by: StephenFroggatt, NorthWest England

Superb solver, really intuitive. Thanks for developing this - from a long term Sudoku fan!

Andrew Stuart writes (15-Jan-2016):

Appreciated Stephen! have a great new year

Friday 1-Jan-2016

... by: shepherdess, USA

I had trouble getting the Daily Sudoku today. A window pops up and says, "Date requested after 31st Decem" but even after clicking "OK," nothing comes up in the puzzle. This is for puzzle # 2922 for January 1. I use Firefox on a Mac.

Andrew Stuart writes (2-Jan-2016):

Sorry about this - and to everyone else. There were a whole lot of puzzle stock that happened to run out at the end of the year and then on top of that, a bunch of date checks which didnít wrap into 2016 as well. Getting it together now I think. Appreciate the alert.
Page:2020 2019 2018 2017 2016 :1 2 3 4 :2015 2014 2013 2012 2011 2010 2009 2008 2007 2006