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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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23 votes
2 answers
2k views

Around the World in Many Days

Deаr Puzzling, How have you been? I am excited to tell you about my new trip. It’s my most ambitious one yet – a full trip around the world! I will definitely keep you posted about my whereabouts. I ...
Jafe's user avatar
  • 78.2k
14 votes
1 answer
884 views

The Blind Killer - a new series! SS#1

An entry in Fortnightly Topic Challenge #47: "Wacky Sudokus" Other puzzles in this series Welcome to a new sudoku series! This series will run for the duration of the current Fortnightly ...
Beastly Gerbil's user avatar
16 votes
2 answers
1k views

Twelve Labours - #02 Lernaean Hydration

This puzzle is part of the ‘Twelve Labours’ series. Previous instalments can be found here: Prologue | 01 His first labour now complete, Hercules made his way up the street to the storage depot for ...
Stiv's user avatar
  • 146k
12 votes
1 answer
772 views

Double feature: Braaains

This puzzle is part 1 of the Double feature series. The series will continue in "Double feature: Russian desman". Rules of Akari (also known as Light Up)1 Insert light bulbs into any ...
Jafe's user avatar
  • 78.2k
15 votes
1 answer
1k views

Heyacrazy: Crosses

This is a Heyacrazy puzzle. Heyacrazy is an original genre, inspired by the "two border" rule of Heyawake and Heyawacky. Rules of Heyacrazy: Shade some cells of the grid. Shaded cells ...
Deusovi's user avatar
  • 147k
14 votes
2 answers
1k views

(1 of 11: Numberlink) What is Pyramid Cult's Favorite Activity?

Dear PSE users and moderators, I’m new here in PSE, but I really need your help. There was this person who gave me a black envelope consisting 10+1 pages of puzzles, and also a scribble saying: “Find ...
athin's user avatar
  • 34.3k
23 votes
1 answer
1k views

Statue Park: Knight's Lines

This is a Statue Park puzzle. Rules of Statue Park: Shade some cells of the grid to form the given set of pieces. Pieces may be rotated or reflected. Pieces cannot be orthogonally adjacent (though ...
Deusovi's user avatar
  • 147k
17 votes
1 answer
886 views

Tapa - Confluence

This is a Tapa puzzle. Rules of Tapa: Shade some cells of the grid. Shaded cells should form a single [orthogonally] connected group; no 2×2 square should be fully shaded. Some cells have ...
Deusovi's user avatar
  • 147k
16 votes
3 answers
2k views

How does one go about creating a new grid-deduction puzzle?

The grid-deduction tag covers puzzles like Sudoku, Kakuro, etc. where the goal is to fill in a grid of numbers [/letters/colours] in a unique way by logical deduction from some predetermined rules and ...
Rand al'Thor's user avatar
12 votes
1 answer
367 views

Follow the path of relation through the grid #1

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
8 votes
1 answer
618 views

A Sincere Nurikabe Puzzle

So here's a standard Nurikabe puzzle. I'll be using the final (solved) grid for my upcoming local puzzle competition logo as it will spell the abbreviation of the competition name. So, what does it ...
athin's user avatar
  • 34.3k
7 votes
1 answer
275 views

Follow the path of relation through the grid #2

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
6 votes
1 answer
224 views

Follow the path of relation through the grid #3

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
106 votes
2 answers
8k views

This new puzzle type needs a name

I believe I have invented a new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by solving the 16x16 sudoku; each of the digits 1-16 must appear exactly ...
Stiv's user avatar
  • 146k
13 votes
1 answer
586 views

Twelve Labours - #07 Cleats 'N' Balls

This puzzle is part of the ‘Twelve Labours’ series, but can be solved independently. Previous instalments can be found here: Prologue | 01 | 02 | 03 | 04 | 05 | 06 Emerging from the barbers with a ...
Stiv's user avatar
  • 146k
60 votes
4 answers
84k views

What is the maximum number of solutions a Sudoku puzzle can have?

I've seen Sudoku puzzles that can be solved two different ways. Referring to a traditional 9x9 grid: Is it possible for a Sudoku puzzle to have more than two solutions? If so, what is the maximum ...
WendiKidd's user avatar
  • 2,483
26 votes
4 answers
2k views

Another new puzzle type needs a name

For an example of how this type of puzzle works, see here... I believe I have invented another new type of puzzle... What is its name? Colour-blind-friendly version available here. Begin by ...
Stiv's user avatar
  • 146k
23 votes
2 answers
689 views

Statue View: Tetrominoes

This is a Statue View puzzle, an original invention combining two logic puzzle genres: Statue Park and Canal View. Rules of Statue View: Shade some cells of the grid to form the given set of pieces. ...
Deusovi's user avatar
  • 147k
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
14 votes
1 answer
588 views

Nurikabe: Hindsight in 2020

This is a Nurikabe puzzle. The goal is to shade some cells so that the resulting grid satisfies the following rules.1 Numbered cells are unshaded. Unshaded cells are divided into regions, all of ...
Jafe's user avatar
  • 78.2k
6 votes
1 answer
290 views

Piece de Resistance - Eight Doubled Tetrominoes Make a Tetronogram

Eight Doubled Tetrominoes Make a Tetronogram This puzzle is part of the "Piece de Resistance" series. Go back to Part 1 (Ace) for the story.Ace Two Three Four Five Six Seven Eight ... Time for ...
Omega Krypton's user avatar
3 votes
1 answer
167 views

Follow the path of relation through the grid #4

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
-2 votes
7 answers
19k views

2x2 row and column equations

Rules: No paper or notes, but a calculator is accepted. Post the exact time min wise of how long it took. And obviously give the answer.
bill bsl's user avatar
  • 569
34 votes
2 answers
3k views

Question 16 Ripple Effect

This is a Ripple Effect puzzle. The rules of this puzzle are: Fill in each region with numbers from 1 to n, where n is the region size. For instance, the top left region must have the numbers 1 to 5 ...
Deusovi's user avatar
  • 147k
29 votes
1 answer
2k views

Captain Pun's new boat

My good friend Captain Pun has bought a new boat. "And this is a picture of its sail!" he said, showing me this: "Solve the nonogram and you'll soon know what type of boat it is!" Can you solve ...
Stiv's user avatar
  • 146k
20 votes
5 answers
1k views

Square Spin #1: Sun and Moon

Defining Square Spin Lets play a game! The aim of this game is to transform one image into another using the least amount of moves possible. Here is what a move consists of: ...
Adam's user avatar
  • 2,907
19 votes
1 answer
656 views

Trichain: Introduction

Next: Trichain: Going Higher Trichain is a new puzzle type I invented. It is somewhat similar to Nurikabe, but it uses a chain of L-trominoes instead of a continuous wall. Example puzzle with ...
Bubbler's user avatar
  • 15.7k
16 votes
1 answer
715 views

Barrel - Part 1

An entry in Fortnightly Topic Challenge #35: Restricted Title 1. Title based on the very first xkcd. Continued in Barrel - Part 2, Barrel - Part 3, Barrel - Part 4, and Barrel - Part 5. You manage a ...
Riley's user avatar
  • 14.5k
13 votes
1 answer
440 views

Nurikabe: A Gentle Walk in the Hall of Giants

This puzzle is a Nurikabe that is designed to be a gentle introduction to the genre, with a learning curve of progressively harder deductions. It is encouraged for first-time solvers and those who ...
Sciborg's user avatar
  • 3,379
12 votes
1 answer
549 views

Cross the Streams: Three?

This is an entry for Fortnightly Topic Challenge #44: Introduce a new grid deduction genre to the community. Here is a standard Cross the Streams puzzle. The genre is invented by Grant Fikes which ...
athin's user avatar
  • 34.3k
10 votes
1 answer
698 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
  • 19.8k
5 votes
2 answers
237 views

Follow the path of relation through the grid #5

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
44 votes
4 answers
7k views

WITLESS - A Puzzling Journey

IMPORTANT! READ ME: The only 'puzzle' parts of this are the links, titled 'Set X', 'Inscription X', or 'Constellation X'. Everything else is flavortext, apart from this readme section, although the ...
TheGreatEscaper's user avatar
28 votes
1 answer
2k views

This new puzzle type needs a name {3}

I believe I have invented** a new type of puzzle... What is its name? ** Well, 'adapted' an existing one, really... Colour-blind-friendly version available here. Those without colour-blindness ...
Stiv's user avatar
  • 146k
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
25 votes
2 answers
2k views

Introducing: Compoundoku!

Rules of Compoundoku: Solve both left and right Sudokus. In addition, the board below them is the Compound Board of both Sudokus. Each number on the Compound Board should tell either: (1) ...
athin's user avatar
  • 34.3k
17 votes
1 answer
825 views

Ingrid Deduction pops by with a puzzle

The other night I was sat at home in Providence when the doorbell rang. To my surprise, my very good friend Ingrid Deduction stood on the step, a huge grin on her face and a piece of paper held out ...
Stiv's user avatar
  • 146k
15 votes
1 answer
764 views

PSE Advent Calendar 2021 (Day 13): A Christmas Hokuro

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation.< Previous Door Next Door > Hokuro is a ...
sarsaparilla's user avatar
  • 6,348
14 votes
2 answers
874 views

PSE Advent Calendar 2021 (Day 4): Decorating with Ingrid Deduction

This puzzle is part of the Puzzling StackExchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 50 reputation. < Previous Door Next Door > "...
Jeremy Dover's user avatar
  • 28.6k
13 votes
3 answers
1k views

What is the minimum amount of numbers needed to create a 4x4 Hidato with a unique solution?

Goal of Hidato: Fill in a grid with a series of consecutive numbers that connect each other horizontally, vertically, or diagonally. So I have been working on figuring out the minimum number of ...
CrSb0001's user avatar
  • 2,423
11 votes
1 answer
725 views

PSE Advent Calendar 2021 (Day 19): Santa's Dilemma

This puzzle is part of the Puzzling Stack Exchange Advent Calendar 2021. The accepted answer to this question will be awarded a bounty worth 100 reputation.< Previous Door Next Door > It was ...
Stevo's user avatar
  • 2,653
7 votes
2 answers
448 views

Square Spin #2: Climb the Mountain!

Square Spin History: #1>#2 New Rules This puzzle introduces two new square types: Unmovable squares (Un) Replaceable squares (Re) Plus the concept of ambiguity! Ambiguity of squares Certain ...
Adam's user avatar
  • 2,907
5 votes
2 answers
237 views

Monday's Dominosa Problem

Dominosa or Domino Solitaire is a logic puzzle with a similar feel to Sudoku. Given a grid of numbers, you have to lay out the dominoes so they match the numbers, without duplicated or missing ...
Don Kirkby's user avatar
  • 2,602
5 votes
1 answer
154 views

Follow the path of relation through the grid #6

There is a relation between rectilinear-adjacent squares such that there is a unique rectilinear path from the top-left corner of the grid down to the bottom-right corner of the grid. Each square can ...
Galen's user avatar
  • 2,296
84 votes
2 answers
5k views

My God, it's full of stars!

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids My dear friend, unknown to us, may have relocated again. He sent me imagery and constellation maps indicating that a distant red ...
paramesis's user avatar
  • 4,629
68 votes
2 answers
5k views

Sudoku like you've never seen it before

I've spent this week trying to create a difficult logic puzzle which is a combination of two Sudoku varaints, 'Samuari Sudokus' and 'Pseudokus', and this combo is unlike anything you can find online. ...
Beastly Gerbil's user avatar
56 votes
1 answer
3k views

Japanese Fusion Alphabet Soup

The Dish... ...is an intriguing blend, with a base of classic Western flavours, and a twist of the Orient at its heart. The Ingredients... ...are diverse and are combined in such an unexpected - dare ...
Alconja's user avatar
  • 37.3k
52 votes
5 answers
5k views

Prime Number Snake

Place numbers 1 to 100 in the cells of the 10 x 10 board below in such a way that consecutive numbers occupy neighboring cells (either horizontally or vertically). Shaded cells should contain only ...
Bernardo Recamán Santos's user avatar
52 votes
4 answers
2k views

Desert Irrigation Project

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids My dear friend researches and designs canal irrigation systems in a remote desert. He's been missing for two weeks. Members of ...
paramesis's user avatar
  • 4,629
42 votes
2 answers
3k views

Q: What kind of logic puzzle would you like? A: Yes

A recent post and Stiv's answer provided inspiration for a new puzzle. I posted a study for this puzzle earlier; this is the bigger effort envisioned. I hope you enjoy! This puzzle consists of four ...
Jeremy Dover's user avatar
  • 28.6k

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