Gun Duel

Mick, Nick, and Rick arrange a three-person gun duel. Mick hits his target 1 out of every 3 times, Nick hits his target 2 out of every 3 times, and Rick hits his target every time. If the three are taking turns shooting at each other, with Mick starting first and Nick second, what should be Rick’s strategy?

Clearly, Mick should not aim for Nick, because if he kills him, then he will be killed by Rick. Similarly, Nick should not aim for Mick, because if he kills him, then he also will be killed by Rick. Therefore, if Rick ends up against alive Mick and Nick, he will aim at Nick, because he would prefer to face off a weaker opponent afterward. This means that if Nick is alive after Mick shoots, he will shoot at Rick.

Thus, if Mick shoots at Rick and kills him, then he will have to face off Nick with chance of survival less than 1/3. Instead, if he decides to shoot in the air, then he will face off Nick or Rick with chance of survival at least 1/3. Therefore, Mick’s strategy is to keep shooting in the air, until he ends up alone against one of his opponents.

Biology Jokes

Who says science jokes are not funny? Below you can see some of the best Biology jokes we know, along with short explanations of the more obscure of them.

Do you know any funny Biology jokes yourself? Let us know in the comment section below.

Two blood cells met and fell in love. Alas, it was all in vein.

A clever wordplay with the words “vein” and “vain”.

Pavlov is sitting at a pub, enjoying a pint. Suddenly the phone rings and he jumps up shouting, “Oh no, I forgot to feed the dog!”

Pavlov is a physiologist who used to ring a bell every time he fed his dogs. After some time, he noticed that ringing the bell by its own caused salivation in his dogs, even if he didn’t offer them any food.

“I wish I was adenine, then I could get paired with U.”

In RNA (Ribonucleic acid), adenine (A) makes a “base pair” with uracil (U).

“What did one sister chromatid say to the other?”
“Stop copying me.”

“Sister chromatids” are two identical chromatids (replicated chromosomes), which are joined with each other.

What does DNA stand for? National Dyslexia Association.

Dyslexia is a reading disorder, which causes various troubles during reading, even for people with normal intelligence. If read correctly, the abbreviation for National Dyslexia Association should be NDA, not DNA.

“What did the stimulus do to the neuron after they got married?”
“It carried it over the threshold.”

The “threshold” is the depolarization level over which a stimulus must carry the neuron, in order for an action potential to be fired.

An infectious disease enters a bar. The bartender says, “We don’t serve your kind here”. The disease replies, “Well, you are not a very good host.”

The word “host” has several meanings, one of which is “a person who accommodates guests”, and another one is “an animal or a plant in which a parasite lives”.

The scientists have just found the gene for shyness. They would have found it earlier, but it was hiding behind two other genes.

“What is the fastest way to determine the sex of a chromosome?”
“Pull down its genes.”

Word play with the words “genes” and “jeans”.

One lab rat says to another:
I’ve got my scientist so well trained that every time I push the buzzer, he brings me a snack.”

“Girl, you are so hot, you denature my proteins.”

When things get hot, proteins denature, i.e. lose their shape and structure.

“What did Gregor Mendel say when he founded genetics?”

Gregor Mendel made his experiments using pea plants.

“What is sleeping brain’s favorite rock band?”

REM stands for “rapid eye movement”, which occurs during sleep.

Vinculus Puzzles

Circles are particles and lines joining them are bonds. The objective is to find all the hidden values, following these four rules:

  1. Particle values must be the sum of their bond values.
  2. Particles can have the following values: 0, 1, 2, 4, 8, 12, 16.
  3. Bonds can have the following values: 0, 1, 2, 4.
  4. If two particles have the same value, the bond between them must have value 0.

The solutions are shown below.

Puzzle Tournament 3

Puzzle Prime’s third puzzle tournament was organized on January 31, 2021. Congrats to Elyot G. who is once again a winner! You can see the problems and the rankings below.

Elyot G.

You have 60 minutes to solve 5 puzzles, each worth 1 point. Upload your solutions as a pdf, document, or image, using the form below. Good luck!

Time for work: 1 hour

1. Constellation

by Raindrinker

Connect the stars with lines, so that the number inside each star corresponds to the number of lines connected to it, and the number in each barrier corresponds to the number of lines intersecting it.

Note: The stars in the corners cannot be connected, since the lines would pass through other stars.


2. Lineon

by Blaž Gracar

Move one of the Friends to the Exit Point.

Draw lines to move Friends. A move is connecting a point on the Grid to another point on the Grid by drawing a straight line. The line can be made in any direction, as long as it connects exactly two points and doesn’t cross or touch another line.

You move each Friend as many times as it says on the Timeline, starting with the topmost Friend and continuing in the order all the way down to the bottom one.

One of the Friends must move to the Exit Point, but before he does that, each of the Key Points must be already connected with a line. A Wall is a double line and no Friend can cross or touch it.


3. Vinculus

by Dr. DJ Upton

Circles are particles and lines joining them are bonds. The objective is to find all the hidden values, following these four rules:

  1. Particle values must be the sum of their bond values.
  2. Particles can have the following values: 0, 1, 2, 4, 8, 12, 16.
  3. Bonds can have the following values: 0, 1, 2, 4.
  4. If two particles have the same value, the bond between them must have value 0.

4. Chess Connect

by Puzzle Prime

The starting and ending positions of 6 chess pieces are shown on the board. Find the trajectories of the pieces, if you know that they do not overlap and completely cover the board.

Notes: The pieces can not backtrack. Two trajectories can intersect diagonally but can not pass through the same square. Only the Knight has a discontinuous trajectory.


5. Murder Mystery

by Hiroji Osaka

In the three murder cases below, you can read the testimonies of all suspects. For each case, find who the killer is, knowing that no 2 people are in the same row or column, and that the killer was alone in a room with the victim.




Elyot G.010113
Leong W.010001
Chandan R.010001


The TOP 3 players will win codes for some of our favorite puzzle video games. Thanks to Other Tales Interactive, Thomas Bowker, and Daniel Nora for supporting our tournament.

Escape the Room: The Cursed Dollhouse


With the huge success of real-life Escape Rooms all around the world, more and more puzzle manufacturers have been trying to recreate the experience with their solve-at-home kits. ThinkFun‘s latest offering, Escape the Room: The Cursed Dollhouse, is possibly the closest you can get to the real thing, so far.

The setup of “The Cursed Dollhouse” is quick and simple. Within a few minutes you get to build a cardboard model of a dollhouse, turn on the recommended soundtrack of creepy music, and light up a few candles to get into the right mood. Once you do this, you can start reading the story of the house and unravel its mysteries.

You begin the adventure in the living room, where you have to solve several puzzles, involving a broken bookshelf, a dusty carpet, and a spiderweb on the wall. Then, you make your way through the rest of the house: kitchen, bathroom, bedroom, until you get to the attic. Each of the rooms you visit contains multiple objects, including hidden ones, which you need to use in order to solve its three challenges. Once you solve a challenge, you get a cryptic symbol which you must enter in the “solution wheel”. Get the three symbols correctly and proceed to the next room.

As you progress, you will encounter various puzzles, including many mechanical ones. You will have to cut, fold, entangle, and do all kinds of fun activities. The puzzles are logical and satisfying to solve. There were one or two which my group found a bit confusing, but fortunately, ThinkFun has created a website, where players can get small hints without spoiling the entire puzzles. In the end, all participants were very happy with the time we spent playing together.

While the price of “The Cursed Dollhouse” is a bit steep, the game provides a lengthy and immersive experience which justifies the cost. It also can be replayed by another group of people using the provided printable forms from the official website.

  • 1-4 players, 13 years and up
  • over 30 puzzles to solve within 2.5 hours
  • realistic small-scale Escape Room experience
  • puzzles are re-printable from the official website


* This post contains affiliate links. We may receive a small compensation if you make a purchase.

Jugs with Water

You have a 3 liter jug, a 5 liter jug, and an infinite amount of tap water. How can you measure exactly 4 liters of water using the jugs?

Call the 3 liter jug “small” the 5 liter jug “large”.

  • Fill the large jug with water.
  • Pour 3 liters of water from the large jug into the small jug.
  • Empty the small jug with water.
  • Pour the remaining 2 liters of water from the large jug into the small jug.
  • Fill the large jug with water.
  • Pour water from the large jug into the small jug, until the small jug is full.

Now there are exactly 4 liters of water in the large jug.