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567 votes
5 answers
70k views

A short, brutal riddle

Left alone, I'm a word with five letters. I'm honest and fair, I'll admit. Rearranged, I'm of no use to trains. Again, and I'm an overt place, warm and well lit. What am I?
Roland's user avatar
  • 9,743
443 votes
4 answers
43k views

This is important. I need you to listen…

Look, you don't know me. We've never met. But, like I said, I need you to listen... I had the most disturbing dream the other night... Woke up in a cold sweat and couldn't get back to sleep. It wasn'...
Alconja's user avatar
  • 37.3k
341 votes
1 answer
17k views

A puzzle in 140 characters

Your final answer will respond to the question "Why don't I like Twitter that much?" Like usual, I'll confirm any sub-answers if you find them Here's the link to the puzzle on Twitter. Here's the ...
stacksfiller's user avatar
  • 10.5k
267 votes
1 answer
31k views

Is this Tetris puzzle solvable?

As a birthday present last year, I received some fridge magnets. They didn't come as a puzzle, so I don't know if they have a solution, but I made a puzzle out of them anyway. The magnets are ...
James Webster's user avatar
264 votes
6 answers
25k views

You have prepared. You are determined. You approach the door

Hints:
Alconja's user avatar
  • 37.3k
240 votes
8 answers
29k views

My prefix is food, my suffix is rude

I thought of this riddle myself. Feedback is appreciated. My prefix is food. My suffix is rude. My infix comes in rounds. I keep you off the ground. What am I?
Riley's user avatar
  • 14.4k
218 votes
1 answer
14k views

An overheard gang meeting, a double agent, and a murder

I was walking home late last night and heard raised voices coming from a boarded up old warehouse. I stopped, out of sight, to listen... [When I started eavesdropping, the conversation was already ...
Alconja's user avatar
  • 37.3k
212 votes
1 answer
30k views

Lock your computer when you walk away!

Well this is strange. I forgot to lock my monitor when I walked away from my desk, at work, and one of my co-workers decided to have a little fun. When I got back, I found this little C# console ...
Khale_Kitha's user avatar
  • 8,442
200 votes
10 answers
22k views

Game of Life: Kill the Sun

Below is an initial state for Conway's Game of Life with a single pulsar. Living cells are white. The area marked with red is your base. You are free to modify any of the red cells, but only those, ...
BaSzAt's user avatar
  • 5,657
196 votes
26 answers
96k views

In the 100 blue eyes problem - why is the oracle necessary?

The riddle Randall Munroe (of xkcd fame) has, a bit hidden on his site, a logic puzzle: A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a ...
dwjohnston's user avatar
  • 2,280
185 votes
3 answers
9k views

Deusovi Honeypot

Looks like the community has spoken. With a heavy heart (as if), I have trapped @Deusovi behind a never repeating, fractally recursive, infinite, unsolvable labyrinth. To keep him busy, I added a ...
Bass's user avatar
  • 77.6k
180 votes
1 answer
11k views

Chaos and Order: a visual puzzle in stained glass

I created a visual puzzle, which my wife then implemented as part of a stained-glass window. I've no idea if it is (a) obvious, (b) stupid or hopefully (c) extremely clever, and hence would love to ...
MattClarke's user avatar
  • 2,033
172 votes
1 answer
10k views

Merlin and Hermes: Mysterious Lines

Two adventurers, Merlin and Hermes, approached a large iron door built into a cliff face."Well...", said Hermes, "What do we do now?". Merlin produced an old, large piece of crumpled paper from his ...
Tryth's user avatar
  • 14k
172 votes
1 answer
15k views

Internship Available!* - Figure out what you're being asked to do before you sign up

Sine waves bound in rectangles shaped into prisms. Mass increases, position changes twice, and mass decreases. The prisms become rectangles and are either discarded or stored for later use. If that ...
Travis Don Kindred's user avatar
169 votes
1 answer
6k views

The Rube Wordberg Machine

Gah! I used to be the brilliant one at Verba Retorta University, but ever since that damned Professor Wordberg showed up, there's been nothing but trouble. And it's all his confounded machine's fault! ...
Alconja's user avatar
  • 37.3k
156 votes
4 answers
12k views

Find the letters that complete these five patterns

Complete the last line in each of the following five series: Puzzle 1: "Using" is E "Desist" is I "Visits" is E "Design" is ??? Puzzle 2: ...
Matt Malone's user avatar
  • 5,143
149 votes
12 answers
22k views

A double-agent with a conundrum

You are a double-agent in the most important war of the 20th century, The Falklands war. For years you have been playing the United Kingdom and Argentinian governments against each other, taking ...
John Meacham's user avatar
  • 1,859
146 votes
2 answers
10k views

A mysterious email from Andrew Void

You are a secret agent in the service of the KGB, about to embark on a highly dangerous mission to infiltrate MI6. You have your disguise, your papers, and your backstory all prepared. The night ...
Rand al'Thor's user avatar
143 votes
8 answers
46k views

How can 64 = 65?

Here is a interesting picture with two arrangements of four shapes. How can they make a different area with the same shapes?
ʇolɐǝz ǝɥʇ qoq's user avatar
142 votes
2 answers
8k views

Hearken, now, and listen close!

Hearken, now, and listen close; I have so much to tell. Now lend an ear and do your job; you surely will excel. To find my hidden message, gaze on every word herein. While skimming through it ...
GentlePurpleRain's user avatar
136 votes
13 answers
24k views

This is it. This is the one. Find your wife

If you have found her, maybe you could try saving her? You come home one day and find your wife is out. You open your computer and discover an email from her. To xxxxx, / Curiosity killed the ...
Beastly Gerbil's user avatar
134 votes
7 answers
53k views

Mensa IQ test question - lines in squares

Which of the 8 tiles below is missing? I've been trying to figure out the answer to this question for quite some time. Can anyone spot the pattern? Source: https://www.bergmandata.com
Mathxx's user avatar
  • 1,449
133 votes
8 answers
24k views

The Sheikh dies

The Sheikh dies, leaving behind three sons, 17 camels and the following order: His oldest son shall inherit one in two camels. His middle son shall inherit one in three camels. His youngest son shall ...
Alexander's user avatar
  • 2,443
130 votes
16 answers
1.8m views

Two doors with two guards - one lies, one tells the truth

You are a prisoner in a room with 2 doors and 2 guards. One of the doors will guide you to freedom and behind the other is a hangman–you don't know which is which, but the guards do know. One of the ...
Rafe's user avatar
  • 5,756
130 votes
1 answer
9k views

How can this shape perfectly cover a cube?

The following shape: can be folded onto the surface of a cube in a way that perfectly covers the entire cube with no gaps and no overlaps. How can this be done?
plasticinsect's user avatar
129 votes
5 answers
142k views

Is this duplo train track under too much tension?

My kids were making this train track of duplo the other day, and this is what they put together. They are still very young, and for them, this is something big. They were really proud that they ...
Lezzup's user avatar
  • 6,386
128 votes
2 answers
14k views

Which country is INDIA in?

An intrepid globetrotter needs to know this: BENIN is in Libya CANADA is in China DENMARK is in the United States FRANCE is in Germany INDIA is in ??
Tom's user avatar
  • 70.4k
127 votes
12 answers
30k views

Paying the Troll toll

You are on your way to visit your Grandma, who lives at the end of the valley. It's her birthday, and you want to give her the cakes you've made. Between your house and her house, you have to cross 7 ...
Shevliaskovic's user avatar
125 votes
1 answer
7k views

A Missing Symbol for This Logo

What symbol should I put in the center to complete this logo?
athin's user avatar
  • 34.2k
125 votes
2 answers
7k views

⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀ ⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀ ⠀⠀⠀⠀⠀ ⠀⠀⠀⠀ ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀...
risky mysteries's user avatar
122 votes
7 answers
30k views

100 Prisoners' Names in Boxes

Names in Boxes The names of 100 prisoners are placed in 100 wooden boxes, one name to a box, and the boxes are lined up on a table in a room. One by one, the prisoners are led into the room; each may ...
Jaydles's user avatar
  • 2,007
121 votes
1 answer
5k views

Paper Picture Puzzle

Here is a puzzle I drew Your final answer will be what you need to know to solve this puzzle (You'll know it when you have the final answer) Notes: I did a couple dumbs. One is the space planning. ...
stacksfiller's user avatar
  • 10.5k
119 votes
13 answers
16k views

If you only have half of me, then I am of no use

People think a part of me is sticky, but I'm not. I do have a sticky friend though. I can create almost anything, but I'm not very creative. After I have done my thing, you can't tell ...
SirDuckduck's user avatar
  • 1,987
118 votes
3 answers
12k views

Prove that π > 3

It seems that once upon a time some politicians tried to pass a law fixing the value of π to be exactly 3. The idea being to "make math simpler so that our children can get better at math". ...
Florian F's user avatar
  • 30.2k
117 votes
8 answers
8k views

Make all the statements true

Can you make all the below statements true with a single click? If yes, explain how. Three + Eleven = Ten Seven + Five = Six Two + Four = Eight NB: 'A Single Click' means, with only a single left ...
AeJey's user avatar
  • 14.5k
115 votes
5 answers
16k views

Mate in 0 moves

Not exactly a traditional chess puzzle, and I won't offer much of an explanation for fear of giving away the answer. White must mate in 0 moves, meaning he must deliver a check mate without touching ...
JGibbers's user avatar
  • 3,742
115 votes
9 answers
16k views

A hunt for long forgotten treasure ...but beware the pirate's curse!

I never really knew my uncle growing up. He seemed nice enough, but I got the sense from the distant, troubled look in his eyes that there was at least some truth to the rumours... Years before I was ...
Alconja's user avatar
  • 37.3k
114 votes
2 answers
58k views

3 Logicians Walk Into a Bar

Three logicians walk into a bar. The barman says, 'Does everybody want a drink?' The first logician says, 'I don't know.' The second logician says, 'I don't know.' What does the third logician say? ...
Bob's user avatar
  • 4,253
113 votes
1 answer
20k views

Cryptic Clue Guide

This post is not a puzzle. There is nothing puzzly hidden inside it or the self-answer, posted at the same time. What exactly is a cryptic crossword clue, and how do I write one?
Deusovi's user avatar
  • 147k
110 votes
1 answer
7k views

This party ends in tragedy (I planned it from the start, you see)

The DJ from Moscow was pumping out tunes. The house mostly bare but for furniture, strewn; A sofa for three and an armchair for one. The guests started piling in, looking for fun... 'Twas ...
Alconja's user avatar
  • 37.3k
109 votes
3 answers
8k views

The brain-curdling eldritch horrors and the third dimension

We're in the year 2016 so it's finally time to take puzzles to the 3rd dimension! So let's see what those beautiful times bring us today: (click to enlarge) Everyone of you clever sods could as ...
Avigrail's user avatar
  • 3,020
107 votes
1 answer
7k views

A strange hotel

Entering the lobby, I requested a room. The clerk handed me my key and I took the elevator to my floor. To my surprise there was a sign on the door of my room telling me I should try a different room ...
Matt's user avatar
  • 1,711
106 votes
9 answers
21k views

Five coloured doors, which leads to freedom?

You have been incarcerated in a high-security prison for several nefarious crimes which we need not go into here. The warden, being a kindly logician, offers you a single chance to escape. You are ...
Rand al'Thor's user avatar
106 votes
4 answers
8k views

Checkmate in 1 on a Tangled Board

Lots of pieces are tangled here. Can you find mate in one? Small hint to guide you in the right way:
shoopi's user avatar
  • 2,675
106 votes
2 answers
7k 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
  • 144k
104 votes
15 answers
41k views

My wife has died

In 1980, a man lives on the 30th floor of his building. Every morning he wakes up, gets ready, kisses his wife, takes the elevator down to the first floor, and goes to work. One morning, he wakes ...
Aggie Kidd's user avatar
  • 11.7k
99 votes
3 answers
10k views

Do I Work with an Orangutan?

This morning I found myself face-down in front of a large building. It was obvious that I had taken a great fall from one of the rooms above me, but now I apparently had amnesia. I went in. I could ...
Chowzen's user avatar
  • 25.7k
96 votes
7 answers
25k views

Why does this solution guarantee that the prince knocks on the right door to find the princess?

I found this puzzle online: On the top floor of a castle lives a princess. The floor has 17 bedrooms arranged in a row. Each bedroom has doors connecting to the adjoining bedrooms as well as to the ...
WendiKidd's user avatar
  • 2,423
93 votes
7 answers
18k views

Thanks, dad! Never again

No idea why my dad dragged me into this place. Some guy is performing on the stage. He's reading numbers out loud. I think it's some kind of a sequence puzzle. 1... 8... 9... 16... 17... ...
Jafe's user avatar
  • 77.3k
93 votes
4 answers
16k views

It's my birthday today - how old am I turning?

It is my birthday today Last year I had 5 candles 4 were lit the last was not But today, I'll light them all How old am I turning today? HINT: I am not turning 5 today and...
ME Ant's user avatar
  • 791

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