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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Skeleton sudoku, the second

I've already set one skeleton Sudoku. Here's a rather harder one. (Nonetheless, it should be within the realms of what can be done by hand; I solved it manually myself to verify that there was only ...
ais523's user avatar
  • 1,987
8 votes
2 answers
1k views

A spartan skeleton Sudoku

A skeleton crossword is a crossword where the black and white squares aren't given; you have to deduce them. Here's a generalisation of that idea to the Sudoku puzzle. Here's a 4 by 4 grid, with four ...
ais523's user avatar
  • 1,987
6 votes
1 answer
354 views

My featured entry

Mosaic is a Minesweeper-like puzzle based on a grid with a pixel-art picture hidden inside. Using logic alone, the solver determines which squares are painted and which should remain empty until the ...
Mordechai's user avatar
  • 712
6 votes
1 answer
645 views

ASCII Art Painting

I've been taking an art course recently, and I met someone who was proficient with grid ASCII art paintings. However, the teacher of the class always seemed to think there was something wrong with his ...
boboquack's user avatar
  • 21.9k
21 votes
2 answers
2k views

Who can spot the difference?

My family and I have just moved house! Lucky us! So what did my family do? We held a housewarming party, and rung everyone in the neighbourhood up to invite them. So, anyway, people were coming in ...
boboquack's user avatar
  • 21.9k
7 votes
3 answers
757 views

Ambiguous Grids

After six to eight weeks of waiting, your Shmikoli™ Ambiguous Grid Deduction Puzzle Set has finally arrived! You tear into the box only to discover that the instructions are missing. You shouldn't ...
DyingIsFun's user avatar
  • 9,176
12 votes
1 answer
758 views

Oriental House: An original grid-deduction challenge

A different approach to an old concept of mine, Oriental House is a new grid-deduction puzzle based once again off exits and entries. The rules are as follows: Draw a path from S to F, passing ...
TheGreatEscaper's user avatar
9 votes
1 answer
2k views

What is a "unique solution" in a Slitherlink puzzle?

In the question Five Slitherlinks, the querent suggests that "each [Slitherlink puzzle has] a unique solution". I'm newly reading about Slitherlinks, but I don't understand what makes a ...
doppelgreener's user avatar
49 votes
4 answers
3k views

Five Slitherlinks

Solve five Slitherlinks, each with a unique solution. Please say a word regarding (or show an image depicting) each solution method.
DyingIsFun's user avatar
  • 9,176
11 votes
5 answers
2k views

Move the coin in the color grid

You need to move the Coin from the S(tart) cell to the END cell. Rules: From S you can move to cells 2,7 or 8. From BLUE cells you can only move ONE space diagonally. From YELLOW cells you can only ...
DrD's user avatar
  • 39.2k
17 votes
1 answer
2k views

Sudoku with only 8 predefined numbers

Have fun with my self-made Sudoku puzzle. Solve this Sudoku puzzle using the standard Sudoku rules: Fill any row, column and bold-framed area with the numbers 1 to 9. Hint: It is not as difficult as ...
Gerhard's user avatar
  • 374
6 votes
2 answers
678 views

Cairo pentagonal tiling logic grid (Edit : with more clues)

Rules : Fill with numbers from 1 to 13, and each number can appear max 4 times. Small numbers between 2 cell shows the difference between the cells. A + D = B + C Example : (In this example, I fill ...
Jamal Senjaya's user avatar
-1 votes
1 answer
1k views

Solve the Mosaic

Mosaic is a Minesweeper-like puzzle based on a grid with a pixel-art picture hidden inside. Using logic alone, the solver determines which squares are painted and which should remain empty until the ...
Mordechai's user avatar
  • 712
40 votes
6 answers
2k views

Sudoku embedded in a Kakuro

In addition to standard Kakuro rules, the grey shaded cells must form a valid Sudoku solution. One sum in this puzzle has been corrected from 28 to 23. Fortunately, it was in a location that nobody ...
paramesis's user avatar
  • 4,609
9 votes
1 answer
2k views

Logic 5x5 Letter Number Combination Grid

Hey I just thought other might enjoy the challenge of this puzzle as much as I did. Not the most easy thing to solve. Sort of like Sudoku, each row and column needs the letters A,B,C,D,E and each row ...
Lain's user avatar
  • 310
15 votes
2 answers
8k views

Creating a Kakuro puzzle with a unique solution

I start with a grid of black and white cells. I randomly populate the white cells from numbers (1-9) using Kakuro rules. Then I calculate the horizontal and vertical sums. I remove the numbers from ...
Surendra Jain's user avatar
12 votes
1 answer
446 views

Is it Pajamas? Or Shampoo? Maybe a Cheetah? Oh I know, it's:

Title hint:
Mordechai's user avatar
  • 712
19 votes
2 answers
1k views

Three for the price of one

While browsing through your local puzzle store, you see something you can't resist: a box which promises two grid deduction puzzles for the price of one! The vendor explains that the box contains a ...
DyingIsFun's user avatar
  • 9,176
27 votes
4 answers
1k views

Curiouser and Curiouser

CHAPTER ONE Alice was beginning to get very tired of sitting by her sister on the bank, and of having nothing to do: when she was overcome with the strangest sense of deja vu, and saw a 7x3 grid of ...
TheGreatEscaper's user avatar
10 votes
2 answers
570 views

Build your own™ Dominosa!

Fictional story: As everybody knows I'm not good at making puzzles so I ordered a Build-your-own™ Dominosa kit! This should be good for my Dominosa building skills, I thought to myself. And today, ...
Wen1now's user avatar
  • 9,253
2 votes
1 answer
741 views

Numberlink strategy

Note: This is not asking for a general strategy, you can find that here. Is the following a valid strategy in solving Numberlink (Flow Free) puzzles (I like to call it 'unwrapping the grid'): ...
boboquack's user avatar
  • 21.9k
22 votes
3 answers
1k views

Introducing Domidoku!

Come one, come all! Come see the new type of logic puzzle, the Domidoku! Here's a sample for all to try! The process is simple! First you solve the Sudoku and then you solve the Dominosa! ...
dcfyj's user avatar
  • 7,756
10 votes
2 answers
274 views

Non-Congruent Fillomino

Here's a Fillomino puzzle (rules can be found here). The gimmick is that no two areas can be congruent. Enjoy!
TheGreatEscaper's user avatar
23 votes
1 answer
2k views

This puzzle design was a DISASTER!

As any member of the PSE community knows, grid-deduction puzzles really aren't my forte. In fact, I'd like to share one particularly disasterous attempt at designing a Slitherlink puzzle. Disclaimer:...
TheGreatEscaper's user avatar
8 votes
3 answers
561 views

Revenge of the Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no relevant order. The solutions to the ...
DyingIsFun's user avatar
  • 9,176
9 votes
1 answer
658 views

Is ambiguity prevention sufficient reason to infer a clue?

I decided to work my way through Simon Tatham's puzzle collection to broaden my puzzling skills, and have reached the game Dominosa I have a subboard below, where I've eliminated the possibility of 9/...
Sconibulus's user avatar
  • 19.7k
4 votes
1 answer
340 views

Treasure of the fancy island

The colored rectangle below is the map of a fancy island. There is a treasure hidden there, but instead of the usual X on the map to depict the location of the treasure you have the following clues ...
Alexandros's user avatar
  • 1,137
9 votes
2 answers
1k views

Haisu: Pixel Perfect

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
TheGreatEscaper's user avatar
5 votes
1 answer
396 views

Haisu: Pink Rose

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
TheGreatEscaper's user avatar
9 votes
2 answers
747 views

Cryptic Crossword Sudoku

This puzzle is inspired by Matt’s excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no particular order. The solutions to the ...
DyingIsFun's user avatar
  • 9,176
11 votes
1 answer
328 views

Dividing up land

Historical records indicate that the brothers Geoff, Petro, and Olaf divided up their large rectangular estate between themselves. Unfortunately, evenly dividing up favorable landmarks resulted in the ...
kaine's user avatar
  • 9,092
5 votes
3 answers
536 views

Haisu: MathGrant

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
TheGreatEscaper's user avatar
29 votes
3 answers
3k views

Coloring a 4 by 4 grid

I made this simple puzzle a couple of years ago. There are three colors which appear in every row and every column. Moreover, every color appears 5 or 6 times in total. Find the color of the square ...
Alexandros's user avatar
  • 1,137
16 votes
1 answer
683 views

Mini Ripple Effect puzzles

I enjoyed this puzzle so much that I created some mini versions of it for fun. I signed up to share them with everyone. The rules are the same: Each region with n cells contains all the numbers from 1 ...
Alexandros's user avatar
  • 1,137
17 votes
1 answer
929 views

HAISU: Nought and Crosses

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
TheGreatEscaper's user avatar
19 votes
1 answer
1k views

A Total Masyu puzzle

In a Total Masyu puzzle, one must draw a single loop through the centres of some cells according to the following rules: The loop may only travel horizontally or vertically, never diagonally; all ...
edderiofer's user avatar
  • 2,361
42 votes
4 answers
2k views

GRID-THIRTY-SIX

Solve 36 puzzles (or more) to find the final 6 letter answer.
TheGreatEscaper's user avatar
47 votes
4 answers
5k views

Who am I??? Wait, isn't this a sudoku?

Jmw jrr qtlf tv ee M6SXr rro tr kz r tyr. Can you find out who I am? Hint 1: Hint 2:
Maria Ivanova's user avatar
14 votes
1 answer
378 views

Broken Masyu: Quartered

Below is an 8x8 Masyu puzzle (rules can be found here), but the puzzle has been broken into four pieces! Can you put the pieces back together to make a proper Masyu puzzle with a unique solution? (The ...
TheGreatEscaper's user avatar
9 votes
1 answer
921 views

Algebra Sudoku: Dozens

Alas, the grid deduction fortnightly is over, but my love for the genre remains the same - i.e. very high. So, here is another grid deduction puzzle. An algebra sudoku! I think the rules are fairly ...
TheGreatEscaper's user avatar
2 votes
0 answers
391 views

WITLESS Inscription 5

2 days ago, TheGreatEscaper had to take down Inscription 5 of WITLESS - A Puzzling Journey, due to (can you clarify TheGreatEscaper?) the lack of a solution. Can anyone think of a valid Inscription ...
boboquack's user avatar
  • 21.9k
7 votes
2 answers
594 views

Making a grid deduction puzzle

When making a grid-deduction puzzle, what are the strategies in making it? For most grid-deduction puzzles, simply putting numbers/dots/whatever in the grid simply doesn't cut it. However, sometimes ...
boboquack's user avatar
  • 21.9k
9 votes
2 answers
975 views

Can you solve this nurikabe puzzle?

Here's a nurikabe for you. Let's see who can solve it first.
Topple's user avatar
  • 600
17 votes
2 answers
817 views

Time to Hit the Bricks!

An entry in Fortnightly Topic Challenge #24: Grid-Deduction... It's 2am. The phone rings. You answer it and are immediately met with an onslaught of franticness from your (in?)famous uncle—a ...
Rubio's user avatar
  • 41.7k
32 votes
6 answers
3k views

A Six-Faced Puzzle

Here is a grid-deduction puzzle, whose mechanics I have seen under several names such as 'Castle Wall', which is the one I'll use here. The goal of Castle Wall is to draw a loop enclosing all the ...
TheGreatEscaper's user avatar
15 votes
1 answer
2k views

Sum in A Sudoku

Color Blind version: Here's a sudoku puzzle with a twist! The numbers given in the squares are actually the sum of the numbers in that region. For example: 18= Sum of the numbers in the 4 yellow ...
Sid's user avatar
  • 15.2k
27 votes
2 answers
2k views

HAISU (Room Count): An original grid-logic challenge

HAISU is a portmanteau of three Japanese words - 'hairu', to enter, 'su', number, and 'hausu', an English borrow word meaning house, of course. Together, we get a meaning of 'enter number house', ...
TheGreatEscaper's user avatar
14 votes
1 answer
2k views

Strategy for solving 0hh1 and Unruly?

Q42's game 0hh1 and Simon Tatham's game Unruly are two almost identical logical deduction games. In each one, we're given a square grid which is to be filled by tiles of two colours, and a certain ...
Rand al'Thor's user avatar
10 votes
3 answers
859 views

A Family Reunion

Names have been changed to preserve anonymity A group of 25 people, A to Y, arrived at Z's door to celebrate the family reunion. They each had something to show off. Z: I know you're all excited ...
boboquack's user avatar
  • 21.9k
5 votes
2 answers
506 views

Simple grid deduction puzzle

I will let you figure the rules of this one yourselves. Here is the empty grid to assist solvers. Here is a text version of the grid: ...
Maria Ivanova's user avatar