How to win at Sudoku

Sudoku Dec 08, 2020

The Christmas holiday season is fast approaching and, weather permitting, that hopefully means lots of opportunity to settle into your favourite spot, crank on your best tunes, fix a nice drink and unwind.  Maybe read a book and perhaps play a few games of Sudoku.

If you’re anything like me you’ve enjoyed the occasional Sudoku over the years and can speed through the easy ones, easily handle the medium ones, but maybe you’ve got a bit tired of the game because you often get stuck on the hard ones.

if that sounds a bit like you then read on, because in this blog post I’ll tell you how to solve most hard and expert Sudokus in 20min or less.  That’s so much better than staring at one for an hour or more before rage-quitting the thing!

To rekindle your relationship, I recommend using good App on your phone or tablet.  I can recommend the free one from  It has ads, but not if you run Pi-hole 😉.  The nice thing about an App is that it’ll generate as many Sudokus as your heart desires, you can choose the difficulty, you get some nice ‘rewards’, and there are no messy pencil marks.

On the pencil mark thing…there is just no way to solve expert Sudokus without marking candidates.  Having said that, the world Sudoku champions power through the puzzles so fast their intuition and pattern recognition makes them super-human.  They mostly just seem to be writing answers.

The picture below is from a World Sudoku & Puzzle Championship 2018 YouTube clip.  If you watch this, you’ll get an understanding of just how amazing some people are.  The only limitation for some of them seems to be how fast they can write.

World Sudoku & Puzzle Championship 2018

I find the better I get at Sudoku the more I enjoy it.  Easy Sudokus are trivial and can be solved with the basic rules written in the newspaper, but the really hard ones require more advanced techniques.  There are at least 70 different solving techniques, but you don’t need them all to solve all puzzles – at least, not unless you want to become a world record holder.  Most of them just speed things up - if you can recognise the opportunity to use them that is – a bit like the special moves that Rubik cube experts use – but you don’t need them all to complete the puzzle.  Oh yes, and as I’m always telling my wife, you never need to guess in Sudoku – ever!  A valid puzzle only ever has one solution and there’s always some logic waiting to be found.  I’m sure Sudoku was invented by a Vulcan in another dimension.

So, how do you learn the special tricks?  Well you need a teacher, and for me that is a really cool open-source computer program called HuDoKu.  You can find it on Sourceforge – the only bad thing about it is that it requires you to install Java (not in your browser though!).  I wouldn’t give it to my mother as it’s a bit on the techie side, but it’s amazing.

HuDoKu is described as “Sudoku generator/solver/analyzer. Lots of human style techniques (singles, subsets, LCs, fish, wings, uniqueness, coloring, chains, ALS), powerful analyzer (manage multiple solutions for one sudoku). Includes Learning and training modes and a booklet printer.”

Just to give you an idea of the depth of this program, it has 6 x Sudoku levels – Beginner, Easy, Medium, Tricky, Fiendish, and Diabolical.  To be honest I’m not quote sure where the App’s ‘Expert’ mode fits in, but I’m sure it’s trickier than medium but not as fiendish as diabolical.  I haven’t tried Diabolical yet.

One of my favourite sayings is “When the student is ready the teacher will appear” and I’d recommend using HuDoKu like this:

1.       Start a Sudoku at a challenging level for you

2.       Go as far as you can until you get stuck

3.       Enter your progress into HuDoKu

4.       Use the ‘Next Hint’ and ‘Execute’ buttons to guide you

The greatest thing about HuDoKu is you’ll learn new techniques.  It doesn’t just tell you the answer, it shows you ‘why’ and the ‘how’.  You’ll get stuck less often, and maybe you’ll find, like I did, the Sudoku rabbit hole goes deeper than you ever imagined.  I’ve included a screenshot of the tool below.  I hope you try it.

HoDoKu - Sudoku generator/solver/trainer/analyzer
HuDoKu - “Sudoku generator/solver/analyzer

Christmas 2020 is upon us and the New Year is just around the corner.  Who knows what 2021 will bring?  Certainly Covid-19 vaccines, and hopefully more peace in the US.  Hopefully also more action against climate change and less plastic!

If you made here well done.  I hope you are lucky enough to get a break in the coming weeks and all of us at vBridge wish you some great R&R, nice food, and good times.  Our office is closed between Christmas and New Year but we look forward to catching up with you again soon 😊

Peter Brook

Peter is our vBridge Operations and Information Security Manager. He has over 20 years experience in many NZ organisations including PGG Wrightson, CDHB, Lyttelton Port Company and Spark Digital.