The Most Difficult Puzzle, Ranked

Choose the puzzle you think is the most difficult!

Author: Gregor Krambs
Updated on Jun 19, 2024 06:33
Considering the broad spectrum of puzzles available, it can be a true challenge to know which ones will truly test your wit and skill. Different puzzles cater to different types of intellectual engagement, from spatial reasoning to linguistic ability. By voting for the most difficult puzzles, users help each other identify which challenges are worth the effort and which ones truly stretch the limits of human ingenuity. This continuously updated ranking serves as a central resource where puzzle enthusiasts can share their experiences and insights. Whether you're a seasoned solver looking for your next big challenge or a newcomer wanting to dive into the deep end, the votes here guide you to what stands as the peak of puzzling difficulty. Your participation shapes this dynamic guide, ensuring it remains a definitive index of the most demanding puzzles.

What Is the Most Difficult Puzzle?

  1. 1

    The Enigma Machine

    A cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military.
    • Inventor: Arthur Scherbius
    • Decryption: Successfully deciphered by Alan Turing and his team at Bletchley Park
  2. 3

    P=NP Problem

    A major unsolved problem in computer science. It asks whether every problem whose solution can be quickly verified by a computer can also be quickly solved by a computer.
    • Formulated: 1971
    • Millennium Prize Problem: One of the seven Millennium Prize Problems
  3. 4

    Voynich Manuscript

    An illustrated codex hand-written in an unknown writing system. The manuscript has been carbon-dated to the early 15th century (1404–1438), and it has puzzled historians, cryptographers, and linguists for centuries.
    • Discovered: 1912
    • Language: Unknown
  4. 5

    The Taniyama-Shimura-Weil Conjecture

    A conjecture that links elliptic curves over the field of rational numbers to modular forms. It played a crucial role in the proof of Fermat's Last Theorem.
    • Implication: Key in proving Fermat's Last Theorem
    • Proved: By Andrew Wiles and Richard Taylor
  5. 6

    Fermat's Last Theorem

    A statement in number theory, formulated by Pierre de Fermat in 1637, that no three positive integers a, b, and c can satisfy the equation a^n + b^n = c^n for any integer value of n greater than two. It was unsolved for over 350 years.
    • Proved by: Andrew Wiles in 1994
    • Published: 1995
  6. 7

    Zodiac Killer Ciphers

    A series of four cryptograms sent to the press by the notorious Zodiac Killer who operated in Northern California in the late 1960s and early 1970s. Only two of the ciphers have been definitively solved.
    • Active Years: Late 1960s to early 1970s
    • Solved Ciphers: Two out of four
  7. 8

    The Riemann Hypothesis

    A conjecture in mathematics that suggests all non-trivial zeros of the Riemann zeta function have their real parts equal to 1/2. It remains one of the most important unsolved problems in mathematics.
    • Proposed by: Bernhard Riemann in 1859
    • Millennium Prize Problem: One of the seven mathematics problems designated for the Millennium Prize
  8. 9

    Beale Ciphers

    A set of three ciphertexts that supposedly pinpoint the location of one of the largest buried treasures in U.S. history. Only one of the three has been solved, revealing the county of the treasure.
    • Published: 1885
    • Treasure: Unrecovered
  9. 10


    A sculpture located on the grounds of CIA Headquarters in Langley, Virginia. Created by artist Jim Sanborn in 1990, it contains four encrypted messages, of which only three have been solved.
    • Artist: Jim Sanborn
    • Unsolved Parts: One section remains unsolved

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About this ranking

This is a community-based ranking of the most difficult puzzle. We do our best to provide fair voting, but it is not intended to be exhaustive. So if you notice something or puzzle is missing, feel free to help improve the ranking!


  • 17 votes
  • 10 ranked items

Voting Rules

A participant may cast an up or down vote for each puzzle once every 24 hours. The rank of each puzzle is then calculated from the weighted sum of all up and down votes.

Additional Information

More about the Most Difficult Puzzle

The Enigma Machine
Rank #1 for the most difficult puzzle: The Enigma Machine (Source)
Puzzles have fascinated people for centuries. They challenge the mind and provide a sense of accomplishment. Some puzzles, though, stand out as particularly difficult. These puzzles push the limits of human problem-solving skills and patience.

The most difficult puzzles often involve complex patterns or abstract thinking. They require more than just basic logic. Solvers need to think outside the box and sometimes even rethink the rules. This makes them both frustrating and rewarding.

One key element in these puzzles is that they often have many possible solutions. This means that finding the right path can be like searching for a needle in a haystack. The solver must sift through countless possibilities. This can take hours, days, or even longer.

Another factor is the level of detail involved. The most difficult puzzles have intricate designs or numerous pieces. Each piece or step must fit perfectly with the others. This requires a high level of precision and attention to detail. Missing even a small clue can lead to failure.

These puzzles also test the solver's persistence. They are not solved quickly. The process can be slow and tedious. Many people give up before reaching the end. Those who succeed often do so through sheer determination.

In addition to persistence, the solver needs a good strategy. Random attempts rarely work. Instead, solvers must plan their moves carefully. They need to analyze each step and consider its impact on the overall puzzle. This strategic thinking is crucial for success.

Memory also plays a big role. Solvers must remember previous attempts and their outcomes. This helps them avoid repeating mistakes. It also allows them to build on what they have learned. Good memory can make the difference between success and failure.

Collaboration can sometimes help. Working with others allows solvers to share ideas and insights. This can lead to new approaches and solutions. However, it can also complicate things. Different people have different ways of thinking, which can sometimes lead to confusion.

Technology has added a new dimension to puzzle-solving. Computers can analyze patterns and possibilities much faster than humans. This has led to new types of puzzles that are even more complex. However, many people still prefer the challenge of solving puzzles without technological aid.

The appeal of these difficult puzzles lies in the challenge they present. They push the limits of human ability and provide a deep sense of accomplishment. Solving one of these puzzles is a true test of skill and perseverance. It is a mental marathon that few can complete.

For those who enjoy a challenge, these puzzles offer the ultimate test. They require a combination of logic, strategy, memory, and persistence. They are not for the faint of heart, but for those who succeed, the reward is worth the effort. The most difficult puzzles are a testament to the power of the human mind.

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