Questions tagged [grid-deduction]

Puzzles such as Sudoku or Kakuro, where the final state of a pre-existing grid must be deduced logically through clues placed within and/or around the grid. Use with the [logical-deduction] tag. For puzzles where you are given a list of clues which can be used to compose a grid to solve them logically, use the [logic-grid] tag instead.

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Regional Business

This is part 40 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The puzzle on the left-hand side is a regional Yajilin. Shade some cells in the ...
Jafe's user avatar
  • 75.4k
9 votes
3 answers
1k views

What kind of puzzle is this?

Hello, I found this puzzle in an old puzzle book, it's fun. Does anyone know if this kind of puzzle has a name, I want to find more, and maybe try making some. Thanks very much! Here is the cover of ...
Rowan's user avatar
  • 91
14 votes
2 answers
1k views

Very small regional Yajilin

This puzzle is part of the Monthly Topic Challenge #14: Think inside the (very small) box!. Rules of regional Yajilin: Shade some cells in the grid. Two shaded cells cannot share an edge, but can ...
Jafe's user avatar
  • 75.4k
7 votes
1 answer
792 views

Before the Common Era

This is part 39 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The grid on the left-hand side is a KenKen puzzle. Fill the grid so that every row ...
Jafe's user avatar
  • 75.4k
4 votes
1 answer
285 views

Nonogram with story

Fellow puzzlers, here's a nonogram I made for you. But it also has a story! Two bored male casino dealers are waiting at the craps table. A very attractive blond woman arrives and bets $20,000 on a ...
cdm's user avatar
  • 159
6 votes
1 answer
215 views

Intermingled primes

This puzzle is part of the Monthly Topic Challenge #14: Think inside the (very small) box!. 6 different, 3 digit primes are stacked here in two layers. You only see the sum of overlapping digits. ...
Retudin's user avatar
  • 7,609
18 votes
3 answers
1k views

Sums in a (very small) box

This puzzle is part of the Monthly Topic Challenge #14: Think inside the (very small) box!. Place the digits 1 to 9 in the box below in such a way that in each row, each column and each diagonal, one ...
Florian F's user avatar
  • 26.3k
-2 votes
1 answer
150 views

What are the largest and smallest numbers in decimal base in this special Sudoku?

I have constructed the following hexadecimal 16×16 sudoku in this site: The rules are like 9×9 sudoku tables (each number and letter should repeat only one time in each column, row, and 4×4 ...
Etack Sxchange's user avatar
12 votes
1 answer
544 views

Musk Oxen and Arctic Foxen

This is part 37 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is an Aquarium puzzle. The grid is divided into “rooms”. Shade some cells in ...
Jafe's user avatar
  • 75.4k
8 votes
1 answer
365 views

gambas al ajillo

This is a Tapa puzzle. That means you must shade some of the squares, so that: No square containing text is shaded. Numbers in a square indicate runs of consecutive shaded squares among the ≤eight ...
msh210's user avatar
  • 11.7k
15 votes
1 answer
324 views

Slither-Yajilink: A match made in Hades

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. This is a Slitherlink-Yajilin hybrid. Shade some cells in the grid and draw one non-crossing, non-branching line ...
Jafe's user avatar
  • 75.4k
15 votes
1 answer
409 views

Seven similar 7x7 (pen-and-paper) logic puzzles

Oh no! I've just finished drafting some 7x7 logic puzzles, but I accidentally dropped all of them on the floor, and now they're all mixed up! To make matters worse, I haven't gotten around to ...
Kusane Hexaku's user avatar
7 votes
1 answer
302 views

A Watery Slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. A watermill is going to be built next to a cozy town. You are the designer of the aforementioned mill/slitherlink, and ...
new Q Open Wid's user avatar
14 votes
1 answer
679 views

Roughing It (Once More)

This is part 36 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The numbers in blue form a Tapa puzzle. Shade some cells in the grid so that the ...
Jafe's user avatar
  • 75.4k
13 votes
1 answer
341 views

Nurikabe: Forties

The good news: It’s my birthday! The bad news: I’m 40 now. It’s not a great update. Just weaker stats with no cool new abilities. Anyway, here’s a Nurikabe to celebrate. Don’t worry, it should be good ...
Jafe's user avatar
  • 75.4k
14 votes
1 answer
334 views

Double trouble - When slitherloops collide

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. What happens when you're working on a couple of puzzles for the Monthly Topic Challenge and try to merge them? Well, in ...
fljx's user avatar
  • 12.4k
3 votes
2 answers
282 views

Why were the Middle Ages called the Dark Ages?

You find yourself trapped in a room, with only one door to escape, and an important question to answer. You are standing on the tile marked with yellow: How to get to the door is the main problem. ...
Lezzup's user avatar
  • 4,914
10 votes
1 answer
298 views

Walking a twisted path on a donut - a Möbius Slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Have you ever wondered why there has to be an "inside" and an "outside" to every slitherlink loop? ...
fljx's user avatar
  • 12.4k
14 votes
1 answer
754 views

Slither-Numberlink: A monstrosity nature never intended

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Rules of hexagonal Slither-Numberlink: Some numbers in the grid are slitherlink clues, some are numberlink clues. Zeroes ...
Jafe's user avatar
  • 75.4k
14 votes
1 answer
487 views

An X x X Slitherlink related to X

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. The final answer is a six letter word. Prefer no partial answers. penpa
Amoz's user avatar
  • 23.1k
4 votes
0 answers
212 views

Are infinite loops possible in the game Prodway?

I'd like to know if infinitely repeating sequences of moves (i.e. cycles) are possible in the following game: Prodway is a game for two players (Black and White) that is played on an initially empty ...
Luis's user avatar
  • 113
7 votes
2 answers
401 views

Are infinite loops possible in the game Reneo?

I'd like to know if infinitely repeating sequences of moves (i.e. cycles) are possible in the following game: Reneo is a game for two players (Black and White) that is played on an initially empty ...
Luis's user avatar
  • 113
16 votes
1 answer
653 views

SlitherLITS: Don't colour outside the lines

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Adding a bit of colour to enhance the loopy goodness of a traditional Slitherlink. Draw a single, non-intersecting loop ...
fljx's user avatar
  • 12.4k
5 votes
0 answers
204 views

Next Sudoku Number

Here is a sudoku puzzle coming from this magazine I found that B5 and B6 can only contain 6 and 7. 8 cannot be in B5 because D1 would be a 8 and neither B3 not C1 could be a 8. I thought it would help ...
Olivier Boissé's user avatar
17 votes
1 answer
947 views

An oddly coloured slitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. I find something strangely satisfying about a well designed slitherlink puzzle, even one which is oddly coloured and ...
fljx's user avatar
  • 12.4k
12 votes
2 answers
1k views

Slitherlink? I hardly know her!

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Rules of hexagonal Slitherlink: Draw one continuous loop in the grid along dotted lines. The line cannot cross itself or ...
Jafe's user avatar
  • 75.4k
22 votes
1 answer
960 views

The Metaslitherlink

This puzzle is part of the Monthly Topic Challenge #13: Variety Slitherlinks. Below is a grid containing multiple small slitherlinks. These can be independently solved to form clues for the large ...
sarsaparilla's user avatar
  • 5,006
6 votes
1 answer
282 views

Is the Parity Sudoku solvable?

I have a new kind of grid puzzle (you could call it a variant of sudoku) I will be calling a Parity Sudoku. Parity Sudoku is played on a 6x6 grid of integer cells with numbers ranging from 1 to 6. It ...
new Q Open Wid's user avatar
12 votes
1 answer
443 views

Sandwiches by the Seaside

This is part 31 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a sandwich sudoku puzzle. Each of the eight different letters in the grid ...
Jafe's user avatar
  • 75.4k
4 votes
1 answer
181 views

Fill the circles with the numbers 4, 5, 6, ... 10

Using all the numbers 4, 5, 6, ... 10 exactly once, fill each empty circle with a number so that if two numbers are in circles that are joined by a line then their difference (in absolute value) is at ...
Will Octagon Gibson's user avatar
11 votes
1 answer
949 views

Make these 30 animals look cool

Place the following 30 animals in the grid: Albatross   Alpaca   Anaconda   Ara   Bear   Bison   Chicken   Dog   Eagle   Elephant   Emu   Hummingbird   Ibex   Ibis   Impala   Kangaroo   Lark   ...
Lezzup's user avatar
  • 4,914
11 votes
1 answer
438 views

Literally-Connecting Wall

This puzzle is a variant on the well-known connecting wall puzzles. May contain traces of grid deduction and happy stars 😊 Rules: Your goal is to fill all the empty squares in the main grid (left) ...
happystar's user avatar
  • 7,240
31 votes
2 answers
8k views

Is this Hashi puzzle unsolvable?

I found this puzzle in my dad's bathroom. The book is "Things To Do While You Poo On The Loo". I think the puzzle is malformed. Here is a Penpa link to an online solver. Is there actually an ...
ConnieMnemonic's user avatar
12 votes
1 answer
377 views

Protected Schooling

This is part 26 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This is a Shakashaka puzzle. Mark some cells half-shaded along a diagonal (one ...
Jafe's user avatar
  • 75.4k
0 votes
1 answer
185 views

Connect colored dots - puzzle

This is a puzzle of connecting all same color dots with each other so all the dots can be connected together and no box can be empty. The connections shouldnt be crossed with each other Below is the ...
Leo's user avatar
  • 19
7 votes
1 answer
371 views

Next logical move in Heyawake

I'm just starting out on Heyawake. On this puzzle, I didn't see the next logical move, so I tried the 3 box with LRL and then RLR and I didn't have any luck going down those bifurcations. What am I ...
Steve's user avatar
  • 71
5 votes
1 answer
255 views

How do I transcribe a KenKen into a Google Sheets?

Similar to this previous question, I have been slowly working through some PDF puzzle books. I will shortly come up on KenKen puzzles (called TomTom in the book, but the format is the same). Here is ...
bobble's user avatar
  • 10.1k
18 votes
1 answer
550 views

Tetromino Jigsaw Madness

This is part 23 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This puzzle is a crossword-jigsaw hybrid. Cover the white area of the grid with ...
Jafe's user avatar
  • 75.4k
13 votes
1 answer
786 views

In It for the Long Haul

This is part 22 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The light grey numbers and arrows from a Yajilin puzzle. Shade some cells in the ...
Jafe's user avatar
  • 75.4k
13 votes
1 answer
968 views

Sardines and Octopi

This is part 21 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The thick black lines in this grid form a LITS puzzle. Shade an orthogonally ...
Jafe's user avatar
  • 75.4k
11 votes
2 answers
360 views

Orthogonally connecting even sudoku digits avoiding squares

Is there a way to complete a sudoku where you have to make sure all even digits are orthogonally connected to all the others, while avoiding 2x2 squares of even digits? It is known to be possible when ...
CAN GÜLLÜ's user avatar
10 votes
1 answer
666 views

Singles, Doubles, Triples

This is part 20 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, The circled numbers in this grid form a Kurodoko puzzle. Shade some cells in the ...
Jafe's user avatar
  • 75.4k
11 votes
1 answer
2k views

Can experienced players tell when a Sudoku was randomly generated? Or if it's a shuffled version?

I'm trying to make a simple classic Sudoku game in JavaScript, and I'm wondering what considerations I should have in how experienced players might interpret the generated puzzles. I'm not very ...
bryc's user avatar
  • 321
2 votes
2 answers
157 views

Hard Sudoku: hint for next number

I tried a hard sudoku and I can't figure out what the next number is. I tried some online tools without any success (I don't want to have the final solution without any explanation). I would be very ...
Olivier Boissé's user avatar
8 votes
1 answer
351 views

Layers upon Layers

This is part 19 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Dear Puzzling, This time I have a Suraromu puzzle for you. The grid contains seven “gates”, ...
Jafe's user avatar
  • 75.4k
10 votes
1 answer
332 views

Boulders in Valleys - Magnetic Confinement

This is a "Boulders in Valleys" puzzle - it's been posted a few times on this site. This specific puzzle's solution has an interesting property that made it quite hard to design. The ...
BaileyA's user avatar
  • 681
14 votes
1 answer
807 views

Sneaks and Addlers

This is part 18 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Deаr Puzzling, This is an I Have No Idea What I’m Doing crossword. The clues are a mix of 10 ...
Jafe's user avatar
  • 75.4k
1 vote
1 answer
159 views

Explanation why next cell has to be a certain value

I'm an absolute beginner and was stuck at the first puzzle of Sven's Sudoku Pad. I reached the following board state, where I noted for every cell which values were possible: After a while I simply ...
Felix Schön's user avatar
9 votes
1 answer
801 views

Paranormal Activity

This is part 15 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Deаr Puzzling, The numbers in blue here form a Nurikabe puzzle. Shade some cells in the grid so ...
Jafe's user avatar
  • 75.4k
10 votes
1 answer
443 views

Coasting Along the Coast

This is part 14 of the puzzle series Around the World in Many Days. Each part is solvable on its own. Deаr Puzzling, The larger grid is a Fillomino puzzle. Each of the six different letters in the ...
Jafe's user avatar
  • 75.4k

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