The January contest is now over. Passwords removed from booklets.

Congratulations to the players who took the top spots, both in Seasoners category (Jaku111, Timothy, Janoslaw) as well as in Beginners (zbych, elena_tens, affpuzz) category.

I am happy to see almost 270 participants!

I am also happy to see that a lot of Beginners were able to solve all Classics within the time limit and also that seven Beginners managed to solve all Variants in time. Well done!

When Deb asked me if I was willing to write a Beginners Sudoku Contest for LMI, I didn’t hesitate for a split second. It meant two challenges for me: First of all, I have never written a classic sudoku before. Second, writing interesting but EASY variants, sounds like a contradiction in itself to me.

Classics
I just started with the classics as I lack experience. It was fun to look for nice patterns of given digits with good solvable sudokus. I wanted the maximum number of given digits to be 27, use different kinds of symmetry and use some unusual patterns.
There is not much to say about it; no dirty tricks, no naked singles (I am not so good in spotting those, and that might be the reason I am not so fond of this technique, and thus don’t put it often in my own puzzles.) Only speed solving skills are required to tackle all four classics. And a lot of you managed to do so.

Variants
When I start making a sudoku variant, one of my goals is to reduce the number of clues to an absolute minimum. Especially for the puzzles I create for the puzzle portal in Germany I do this very often. The only exception to this rule is when symmetry is broken by removing a clue.

But for the puzzles that are part of a Beginners Contest, I had to let go this rule pretty soon; the puzzles would have become too hard that way. For example: the irregular didn’t have the 6 and 4 in the centre in the First version and the killer had the two cages of 6 combined to one of 12 in rows 2/3 and cages 10 and 9 combined to one of 19 in rows 3/4/5. Both puzzles were too hard, so I repaired the difficulty level by placing extra givens and by splitting the cages.

Some notes to some of the variants:
Untouch: the untouch rule is necessary only a few times. Mainly normal sudoku solving techniques are used.

XV: For this puzzle the 3 centre columns can be filled very quick. The blocks 1 and 9 provide a lot of information so you can proceed very fast after that. Especially when using the information where there is no X or V.

Killer: I am fond of larger cages and I love diagonal symmetry. I think eight cages of size two is pretty much the minimum for keeping it a quickly and smoothly solving puzzle. In my original puzzle there was a bigger role for the cage 28/7 in the center in combination with the cages 11/3 and 16/3 sticking out of the 3x3-block bottom right. Incredible to see that the fastest solvers tackled this one in around three-and-a-half minute!

It was my pleasure to create this Beginners Contest for you. I hope you all enjoyed it!

The 3rd Sudoku, XV has 2 good results, please check ! :)
326914578
497865123
158732649
814659237
735281496
962473851
689547312
243196785
571328964

Completely clueless about which Sudoku XV you are referring to. Please provide a link.

Pretty sure this is the XV Sudoku from the last WPF GP.

Frantz, all instances of X and V are given, so there can't be any digits adding to 10 or 5 anywhere in the grid except where the X's and V's are given. Because there are numerous places two adjacent digits add to 5 and 10 in your solution, where no X or V is given, you solution is not valid.

I hope this helps.

Nice Tough sudokus.Thankful that Grand prix Indian round got completed just before this.Could carry on the momentum comfortably .I could almost feel instinctively where the numbers would be hidden.Ah Hidden singles again all over the place!!!Lovely construction
Some very really narrow points in the sudokus.Thankfully i found them sooner without wasting much time.
Overall CLASSIC classics!!!!!

The instructions on the "Frame Sudoku" for the on-screen solving (not the pdf) are wrong.
They're instructions for a Killer rather than a Frame.
It could definitely cause confusion for anyone who is expecting the instructions to remind them how Frame works.

I liked this test very much esp. the Classic puzzles. Each classic puzzle was very well created to give the minimum required hints. Extra Region Sudoku was nothing but Windoku itself. I think we could have introduced this type in this test instead of saying it as Extra Region Sudoku. I also liked the Frame Sudoku. Rest Sudoku XV and Irregular were easy ones. Overall very enjoyable Test. Thanks to Deb, Prassanna and LMI for this great test.

That is an interesting observation. Not sure if Prasanna designed it that way.

Puzzles were nice. Alas, I was hung up on the Frame Sudoku for quite a while due to my own silliness (when you need 2 pairs for a 7-sum, don't pick 2+6 and 3+5 :))

Hi :)
I'm new to LMI
I prefer to solve online but I'm not familiar with your online interface, can you please tell me how can I delete a pencil mark?
I tried "Delete" and "Backspace" and none of them can delete a pencil mark :p

For removing a pencil mark, you can press Ctrl+digit or Ctrl+leftClick. Its given in the "How to Submit?" section of the submissions page. :)

Thank you :)
found the point and solved the test online last night :D

Disappointed in my performance in part one. Decided to give it a try after getting my 10-month old to bed, and he of course woke up 30 minutes into the thing. Having to shoo the neighbor's cat off a couple of times didn't help. Oh well. Guess I may eventually learn not to do these when I'm the responsible caretaker. :)

Beginners' Contest February is over. DavidCollison, Bram28 and Tokeiya take the top spots among the Beginners. f4han, Timothy and Gotroch take the top 3 Seasoner spots with some incredible times as always. Congratulations to all the winners.

This Beginners' Contest had a high participation of 318, among which 135 are beginners.

This was the first Beginners' Contest where I contributed as an author, and as I still needed work on my Classic side, Deb kindly agreed to contribute that half and came through with some high quality classics. As for the variants, I feel Frame Sudoku can be an inherently difficult type, because a lot of it involves triplet-thinking, and so I tried to make the other variants on the easy side. This particular Frame sudoku has a tricky few steps around the 3rd box, but otherwise its pretty smooth. Its important to note the hidden sums too in Frames, and there were a few helpful ones here, like the hidden 24 in row 1 for example. Anyway, I hope everyone enjoyed both the classics and the variants.

Thank you all for participating!

Thank you to you, Deb and the other organisers for a very enjoyable contest. Finding a Windoku as the Extra Regions puzzle was a pleasant surprise. I found the Frame puzzle heavy going for a while, but it really taught me the value of triplet-thinking as you mention : in general when dealing with variants, it's normally helpful to also remember to apply the basics such as rows, columns and blocks summing to 45 (including the middle block in this case).

David

If I read the Renban rules correctly, a line which is a closed loop in a 3x3 block is impossible (since consecutive digits in a block must be a chain, which cannot possibly close as a loop). What am I missing?

Please note that order of digits inside the line does not matter.

Passwords removed from booklets.