Where to find hard Sudoku puzzles

Number games like Sudoku are a fantastic way to keep your mind sharp and test your brain power, especially if you're advancing to the more difficult levels with fewer given numbers at the beginning. In addition, these puzzles can help fight cognitive decline, improve concentration, and reduce stress in your day-to-day life.

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Where to find hard Sudoku puzzles
  • Sudoku is a great way to keep your mind sharp and test your brain power.
  • Sudoku apps on your phone are a convenient option for travel entertainment.
  • You can print out online Sudoku puzzles if you prefer physically completing them.
  • The best way to solve a Sudoku puzzle is to start with the easy solutions and work your way up.

Topic: FAQs

  • How hard is it to solve a Sudoku?

    The difficulty level of Sudoku depends on how many squares are filled in at the beginning and the techniques needed to finish the puzzle. Beginners may find it challenging to complete an easy puzzle because it's easy to miss simple mistakes.

  • What is hard level Sudoku?

    Hard level Sudoku usually means only a few numbers are given at the start. Having fewer options at the beginning might mean you must use different solving techniques to finish the puzzle.

  • What is the best way to solve a Sudoku puzzle?

    The best way to solve a Sudoku puzzle is to start with the easy solutions and work up to the more complicated techniques. Constantly re-evaluating the notes you’ve made will help to make sure you don’t miss any easy options or mistakes.

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There are a few different places you can find hard Sudoku puzzles. You can either complete the puzzles within the website or app suggested or print out the puzzle to complete with pencil and paper. 

5 websites and apps for playing hard Sudoku puzzles

1. Sudoku.com

Sudoku.com is an excellent website for finding Sudoku games of any level, ranging from easy to "evil" puzzles. The hard level on Sudoku.com is difficult for new players, but using the Sudoku techniques we'll explore later, you should be able to solve these with some practice. The harder a Sudoku puzzle is, the more empty cells there will be in a new game, making your first steps much more cryptic. The "expert" and "evil" levels on Sudoku.com require various techniques to solve these puzzles, and even experienced solvers may struggle with the “evil” level Sudoku puzzles.

2. NYTimes.com

The NYTimes website also offers some of the best Sudoku puzzles with a higher difficulty level, alongside an easy and medium level.

3. Microsoft Sudoku

You can use Microsoft Sudoku offline or with the Xbox network if you have an Xbox account. It has six difficulty levels and several modes, including a "Sudoku of the Day".

4. Sudoku Pro

Sudoku Pro has five game modes and a few difficulty levels. It offers hints and a draft mode with customisable backgrounds and themes. 

5. Puzzazz

Puzzazz has Sudoku puzzles with varying difficulty levels. It also has other puzzles like crosswords and word searches.

How to solve hard Sudoku puzzles

If you’re searching for hard Sudoku puzzles, you probably already know the basics of Sudoku. However, there are a few Sudoku tricks and techniques that you might need to know to solve the more difficult puzzles.

Pencilling In/Notes

This is one of the more straightforward techniques and means adding a list of "candidates" to each square for which numbers potentially fit. This helps eliminate options as you go. 


Crosshatching eliminates the rows and columns where a number cannot go to see the squares left where the number could fit. 


Slicing is similar to crosshatching and uses the same technique but grouping three boxes at once and trying to place each number from 1 to 9 in as many boxes as you can.

Doubles and Triples

If two squares in the same box, row or column have the same two options in both squares, you can remove these numbers from any other potential squares. This is called doubles.

Three squares in a box, row or column can also form a “triple”. A triple is when all three squares have the same three number options. This means you can remove the numbers in the "triple" from any other potential squares outside of it.

XY-Wing or X-Wing Strategy

This is a more advanced technique for eliminating options, using two parallel rows or columns rather than blocks. So, for example, if you have a row with the same options in two spots and another row mirroring this, you can eliminate similar options in the columns passing those spots.


The swordfish technique is an even more advanced version of the x-wing strategy, using the same idea but with three sets of squares instead of two.

Is Sudoku good for your brain health?

Sudoku has many different benefits for your brain health and cognitive functioning. For example, studies by the National Library of Medicine have shown that both the lateral and medial prefrontal cortex regions are activated during a Sudoku task, meaning you can use Sudoku for cognitive remediation training. 

Sudoku is not only a useful technique in helping with psychiatric disorders, but it can also help with day-to-day brain function. 

Here are some things Sudoku can positively impact on your life and brain health.

Improving your concentration 

Sudoku requires a lot of concentration and logical thinking, so practising your focus by completing these puzzles can also help improve your concentration skills.

Stimulating your brain 

We all know physical exercise is vital in boosting your health and stimulating your body, but it's also essential to stimulate your mind. Sudoku is an excellent tool for this as it requires a problem-solving mindset.

Improving memory 

Sudoku puzzles can be a valuable tool to boost your memory skills, as you constantly need to think of which strategies are best and how to use them. Although you may take notes of number candidates for each square, you may need to do this less with practice as you remember the number of options yourself. 

Problem solving skills 

Sudoku can offer new ways to look at problems, and pushing yourself to try more difficult puzzles means you must start using new problem solving techniques. Constantly learning and applying new techniques may help you with logical thinking in solving problems in your day-to-day life.

Fighting mental decline

Sudoku keeps your brain active and can help with fighting against Alzheimer's and dementia. 

Reducing stress and anxiety

Taking the time away from a stressful situation to focus on a stimulating puzzle may help reduce your anxiety and stress levels. Re-focusing your attention could even help you get back to solving the problem once you finish your puzzle. 

A sense of accomplishment and triumph 

We all enjoy solving a problem, beating a puzzle, and winning a game. Sudoku is no different, especially once you start completing the puzzles with a higher difficulty level in a shorter time. 

Using the tricks and techniques for solving challenging Sudoku puzzles, you should be able to complete all of the hard puzzles on the websites and apps we suggest. However, the "evil" puzzles might still be a tough challenge, even for experienced players.

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