34 votes
Accepted

The Devil's Shell Game

Do we need the restriction that left and right can not be swapped directly?
ralphmerridew's user avatar
18 votes
Accepted

Invalid Jigsaw Sudoku Layout

The given jigsaw layout may be proved invalid using a solving technique I learned by watching Cracking the Cryptic.
codewarrior0's user avatar
  • 6,599
16 votes
Accepted

An unusually tricky Galaxy

That was a nice one. Made easier for me by the fact that you said it was hard! Start with the obvious reflections: The third square on the top row can only be associated with one of two centers, so I ...
Dr Xorile's user avatar
  • 23k
14 votes
Accepted

Mercury in Centigrade

The solved sudoku looks like this: The key to start the sudoku is From here it is easy to solve the rest. After solving the sudoku, So Gladys is visiting
ACB's user avatar
  • 6,301
14 votes
Accepted

Continue a hard Loopy/Slitherlink puzzle without brute-force

Look at the red circle pictured below.
Jaap Scherphuis's user avatar
14 votes
Accepted

Add rules to Minesweeper until you can start with nothing

A grid that satisfies the condition is We can click on
Jujustum's user avatar
  • 3,505
13 votes

The Devil's Shell Game

Setting aside the trivial case where the bead is under the skull with the gold tooth, we observe that: So given that we know the starting and ending position of the gold skull, the starting position ...
SQLnoob's user avatar
  • 7,972
9 votes

Murder Mystery. Who is the killer?

I think it was because
SteveV's user avatar
  • 15.8k
7 votes

Continue a hard Loopy/Slitherlink puzzle without brute-force

I realize that the intended solution has already been revealed in a comment, but since I also discovered it and it has not been described in detail in an answer, I thought I might as well add it. Have ...
Christoph's user avatar
  • 3,871
7 votes

The Devil's Shell Game

Therefore:
Truej's user avatar
  • 532
7 votes

Lions vs. Pokémon

I think the answer is Proof of lower bound Proof of upper bound
hexomino's user avatar
  • 135k
7 votes
Accepted

Is the 7-clue 6x6 Sudoku solvable?

It is... Here are two: Notice that some of your progress is too strong. In fact, it turns out that...
RobPratt's user avatar
  • 13.2k
6 votes

An Irregular Colombian Sudoku

Solution: Step by step: 1: 2: 3: 4: 5: 6: 7: 8: 9:
Beastly Gerbil's user avatar
6 votes
Accepted

Light Up (Akari), but on a real projective plane!

I believe this works:
SQLnoob's user avatar
  • 7,972
5 votes

The Devil's Shell Game

My solution's not as neat as ralphmerridew's because it relies on the fact that the outer two skulls can't be swapped:
Goldstein's user avatar
  • 151
5 votes
Accepted

A Spelling Bee Champion And Some Bewildered Children

fljx's user avatar
  • 15.8k
5 votes

Continue a hard Loopy/Slitherlink puzzle without brute-force

Similar location, but different reasoning path:
justhalf's user avatar
  • 6,034
5 votes

Lions vs. Pokémon

Here is an improvement over hexomino's answer. I.e. a simpler one. That this is minimal has been explained by hexomino. This is how it is achievable.
Florian F's user avatar
  • 28.4k
4 votes
Accepted

The Minesweeper Puzzle That Might Stump People

Parcly Taxel's user avatar
  • 7,359
4 votes

Mr. Martin And The Mismanaged Airport Terminal

This is not an answer to the puzzle itself but instead a response to request for feedback. Please note that my feelings are quite subjective and are coming from someone who couldn’t finish the puzzle. ...
Toffee's user avatar
  • 1,162
3 votes
Accepted

Mr. Martin And The Mismanaged Airport Terminal

Took me a while, but here's the solution: Step by step: As for feedback, I really enjoyed this riddle. The only thing I'd change is to make it a bit more clear how the swapping works. It says that ...
PebNischl's user avatar
  • 511
2 votes
Accepted

Make numbers 1 - 30 using the digits 2, 0, 2, 5

I haven't used $\sqrt{\ }$, nor any double/triple factorial.
Jaap Scherphuis's user avatar
2 votes
Accepted

What can I deduce next about this daily Light Up (Akari) puzzle? (Feb. 22, 2024, 7x7 Hard)

Beastly Gerbil's user avatar
2 votes
Accepted

What can I next logically deduce in Day 62 of the Minesweeper Advent Calendar? (Fake 3D)

Chosen Convention: (x,y,z) z for plane (1,2,2) is not a mine (1,2,1) is a mine. Reason: There is a 1 at (1,3,1) which means either (1,2,1) or (1,2,2) is a mine. There is a 2 at (1,3,2) which means ...
Harshal Narsaria's user avatar
1 vote

An unusually tricky Galaxy

Here is one immediate deduction. Not sure how to continue.
daw's user avatar
  • 3,178
1 vote

What can I next logically deduce in Day 62 of the Minesweeper Advent Calendar? (Fake 3D)

Here is a start
Florian F's user avatar
  • 28.4k
1 vote

The Devil's Shell Game

Assume that both left-center and right-center swaps can be used in the same game.
tolos's user avatar
  • 251
1 vote

The Devil's Shell Game

A basic algorithm is the following one. There is a wrapping mechanism here: for skulls ordered as A, B, C, the skull at the left of C is B, and the skull at the right of C is A. The solution is ...
mountrix's user avatar
  • 313
1 vote

Murder Mystery. Who is the killer?

I believe it was Here is my chain of thought What the scenario possibly could have been Some final thoughts
Conundrumania's user avatar
1 vote

Murder Mystery. Who is the killer?

I think it was motive: means: opportunity: deduction:
oopoopoop's user avatar

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