Gareth Moore
Dr Gareth Moore is the author of over 20 best selling international puzzle and brain-training titles from a wide range of publishers. His titles include: Keep Your Brain Fit: 101 Ways to Tone Your Mind – Duncan Baird (UK, US) The Mammoth Book of Brain Workouts – Constable & Robinson (UK) / Running Press (US) Train the Brain: Use It or Lose It – Michael O’Mara (UK) The Little Book of Sudoku Volume 4 – Michael O’Mara (UK) The 10-Minute Brain Workout – Michael O’Mara (UK) Kakuro for Beginners – Hodder Children’s (UK) (2 books; red and blue) The Book of Japanese Puzzles – Michael O’Mara (UK) / published in the US by Simon & Schuster as The Essential Book of Japanese Puzzles The Book of Hitori – Michael O’Mara (UK) Quick Kakuro – Michael O’Mara (UK) / published in the US by Simon & Schuster as The Essential Book of Kakuro 2 The Book of Hanjie – Michael O’Mara (UK) / published in the US by Simon & Schuster as The Essential Book of Hanjie The Book of Kakuro – Michael O’Mara (UK) / published in the US by Simon & Schuster as The Essential Book of Kakuro Kids’ 10-minute Brain Workout – Buster Books (UK) / published in the US by Simon & Schuster as Sudoku Makes You Smarter! The Kids’ Book of Hanjie – Buster Books (UK) / Simon & Schuster (US) The Kids’ Book of Number Puzzles – Simon Scribbles (US) / Buster Books (UK) The Kids’ Book of Kakuro – Buster Books (UK) / Simon & Schuster (US) The Kids’ Book of Sudoku! Challenge Edition – Simon Scribbles (US)
Homepage: http://www.garethmoore.co.uk/
Posts by Gareth Moore
Toroidal Sudoku
May 28th
Sorry for the lower quantity of puzzles this past week – I’ve been working on completing a new book so I’ve had to focus on that instead, but next week I’ll hopefully get back up to my five-a-week average! I’m not feeling very inspired in terms of being too original right now so I thought I’d post a ‘regular’ 9×9 toroidal Sudoku, although this one is a little tricky through having only 14 given numbers to start from!
As my easy and hard puzzles attest, I’ve been doing a lot of work on really accurately rating Sudoku puzzles, something which I’ve only done in a more general way before on the basis of what logic was necessary to solve a puzzle – now I can do a much more detailed analysis of the number of simultaneous possible moves at any stage of solving the puzzle, what those moves are, and at what point in the solve process they’re required. I needed this new accuracy of rating for one of my new books that will be out later this year (actually pretty soon, at the start of July), shown left – Hard-as-Nails Sudoku. It has over 200 really-difficult puzzles – they start out tricky (more than 10 minutes to solve) and end up… well, even harder than the tough puzzle I posted last week! But at no point do they use any ‘unfair’ solving logic – they stick fair and square to logic that any solver could come up with themself, without help. And of course, no guessing is ever required.
Anyway, it doesn’t take a complex analysis to see that today’s toroidal is not going to be on the easy side, given the low number of givens and the fact that toroidal puzzles really do twist things up in a difficult kind of way – so good luck! 
The opposite of difficult
May 27th
After last week’s very difficult Sudoku, I thought it would be fun to try the complete opposite – an extremely easy Sudoku! At all stages of this puzzle there are lots of possible places to go, which means that your target time to beat (if you care to try) is two and a half minutes.
If you’re interested, I solved it in 2:13 but that included correcting for a careless mistake where I added two ‘4’s to one of the boxes! I’m probably twice as slow as the world’s best solvers so whilst I’m certain some of them could manage it in under a minute, I think anyone who manages it in under 2 minutes should be very proud!
Of course, it’s just for fun and if you have an off day it could take you as long as 3 minutes….. 
Good luck!
Samurai Star
May 23rd
You might be pleased to know that today’s puzzle is somewhat easier, despite being a lot bigger! It’s actually possible to comfortably solve this without making a single pencilmark, if you fancy an extra challenge.
It’s a Samurai Star / Flower Samurai puzzle. Just place 1 to 9 into each row, column and 3×3 box of the 5 underlying grids (there’s one in the centre too).
Good luck!
Just a Sudoku… how hard do you find it?
May 21st
Following yesterday’s theme of scaling back to simpler puzzles, here’s a plain and simple Sudoku.
It might not be an unusual type of puzzle, but it’s interesting to me because I’m trying to calibrate the difficulty of tougher puzzles whilst avoiding solving strategies that casual solvers won’t know – I don’t want to make difficult puzzles simply by requiring obscure logic! (There’s nothing wrong with that in itself, but it’s not what I’m trying to do here). I’ve never put much effort into making really hard puzzles, mainly because it’s a minority interest and it’s not one I personally share too much (I like to get stuck, but not for too long! ). In general I’d rather my puzzles be tricky because they’re unfamiliar or are novel in some way.
Anyway, after a few easy placements this puzzle gets quite hard to make progress on – or so I think. I’d really, really like to hear how difficult (or not!) you find this puzzle, and how long it takes you to solve it. (I’ve also added it to puzzlemix.com if you’d like to play it online).
Thanks, and good luck!
Samurai Sudoku
May 20th
I thought it would be nice to have just a regular puzzle for a change – so today’s Sudoku is a standard, vanilla 5-grid Samurai Sudoku, without any twists!
Just place 1 to 9 into each row and column of the 5 underlying 9×9 grids, and 1 to 9 into each of the bold-lined 3×3 rectangles.
Good luck!
Wrap-around Consecutive 3-grid 6×6 Samurai Skyscraper
May 18th
Wrap-around Consecutive 3-grid 6×6 Samurai Skyscraper puzzle
Another mouthful of a puzzle name, but in essence simply a development of the previous puzzle I posted. This time we still have the wrap-around consecutive-ness, but I’ve extended it to a samurai puzzle and added in skyscraper clues. To keep it reasonable, I’ve reduced the underylying Sudoku size to 6×6, however!
What’s particularly fun about the wrap-around markers is that they warp from one side of the puzzle to the same row/column on the opposite side – for the centre two columns this means that they constrain the values of two numbers 10 squares apart.
So the full rules are:
- Place 1 to 6 into each row, column and 2×3 bold-lined box of each of the three underlying 6×6 grids
- White bars show that adjacent cells are consecutive – i.e. 1&2, 2&3, 3&4, 4&5 or 5&6; those squares without a white bar between are non-consecutive
- White bars are shown where appropriate even on the edges of the grid – they indicate how the cell relates to the square at the far end of this row/column of numbers. Remember that the lack of such a white bar means that these wrap-around squares are non-consecutive.
- Skyscraper clues reveal how many numbers can be ’seen’ from that clue number counting in along the adjacent row/column, where higher numbers obscure all lower numbers (see previous puzzles for more detailed instructions)
Just to clarify, if adjacent numbers are equal (which is possible if they’re at far sides of the grid from one another) then these count as non-consecutive.
Good luck!
Consecutive Wrap-Around Sudoku
May 16th
Consecutive Wrap-around Fiendish Sudoku puzzle
Here’s a slight twist on Consecutive Sudoku – I’ve included ‘wrap-around’ consecutive indication, where rows that start and end in consecutive digits have a white bar at the start and end of the row to show this, and similarly for columns. If they’re non-consecutive then there is no white bar. Similarly between all other squares: a white bar indiciates that two squares are consecutive, and no white bar means that they are non-consecutive.
‘Consecutive’ means that the difference between the numbers is ‘1′, i.e. they are 1&2, 2&3, 3&4, 4&5, 5&6, 6&7, 7&8 or 8&9. Other than this it’s a regular Sudoku – place 1 to 9 into each row, column and bold-lined 3×3 box.
This is also a difficult Sudoku, so if you can solve it under 20 minutes that would definitely be good going. Don’t forget about the non-consecutiveness – this is very important to reach the solution, and don’t forget about the wrap-around!
Good luck!
Something completely different – a word wheel
May 14th
Just for a change from Sudoku, I thought I’d upload a different type of puzzle today (I might also add a Sudoku variant later, if I have time!). This is a more traditional type of puzzle – a word wheel.
The idea is to form as many words as you can by using a selection of letters from the wheel no more than once each per word – and every word must include the centre letter. Words must be 3 letters or longer, and be a regular English word. For example in the wheel here we could form “LAD” as one of our words.
I found 24 words. Bonus points if you can spot my choice of 9-letter word that is in there! (or perhaps that should be a negative bonus if you don’t! )
Double Toroidal Killer Sudoku Pro 8×8
May 13th
Double Toroidal Killer Sudoku Pro 8×8 puzzle
This puzzle certainly won’t be to everyone’s tastes, but it’s a double toroidal killer sudoku pro. Why double? Because there are toroidal jigsaw-shaped Sudoku regions, and there are toroidal jigsaw-shaped Killer Sudoku Pro cages. In other words, some of them wrap around the edges of the puzzle. It’s also an 8×8 puzzle, just to keep the Killer Sudoku (Pro!) logic fresh.
The rules are as you might expect:
- Place 1 to 8 into each row, column and bold-lined shape – some of these shapes are toroidal, so wrap from the end of one row/column to the opposite end of the same row/column
- Place numbers into the dashed-line Killer Sudoku Pro cages so that when the given operation is applied the result is the stated number. For ‘-’ operations start with the highest number.
- Numbers can’t repeat in dashed-line cages, and some cages (just one in this puzzle actually) are toroidal, so wrap around the rows/columns as described above
And that’s it! Good luck!
Hints: As always with this sort of puzzle, if you shade in the 8 bold-lined regions first with different colours you’ll find it much easier to keep track of what you’re doing. Also, all of the regions (both killer cages and bold-lined regions) have rotational symmetry order 4 – in other words, the same pattern repeats 4 times; this might help!
Toroidal Killer Sudoku 10×10
May 12th
Toroidal Killer Sudoku 10×10 puzzle
So far all of the “pure Sudoku logic” in my puzzles posted here has been pretty gentle. Well I decided that it was time to change that, but of course I wasn’t about to do that with a common garden puzzle! So I’ve applied some harder logic to this 10×10 Killer Sudoku with toroidal cages.
Because this is a 10×10 puzzle I’ve kept the Killer Sudoku part very easy – there are plenty of single cages (with apologies to those who dislike these!) and although the maths goes a tiny bit higher the actual ‘Killer reasoning’ is straightforward. But the Sudoku reasoning itself is definitely tougher, in places.
So here are the rules:
- Place 1 to 10 into each row, column and bold-lined 5×2 cage
- Place numbers so that they add up to the total at the top-left of each dashed-line cage
- Numbers may not repeat within a dashed-line cage
- Some cages wrap around the edges of the puzzle – they continue in the same row/column on the opposite side of the puzzle (so a cage leaving off the right of row 3 continues on the left edge of row 3, and vice-versa)
In summary, then, there are a few relatively unusual things here: the 1-10 Killer sums and 1-10 Sudoku; the toroidal cages; and the fact that this Killer requires tough Sudoku logic and so plays more like a 1-10 regular Sudoku than a 1-10 Killer… once you get going, that is!
Good luck!
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