Fortnightly Topic Challenges are all water under the bridge now, so we will do something completely different.

What to Do:

If you have an idea for a tag or a theme of any kind to use as a topic challenge, post it as an answer below. (Do note, you can propose anything, not only a tag). Each answer should start with the title of the topic in a markdown heading (## Title ##). Only one suggestion per answer, please. Here is a list of all tags, to help.

At the start of each month, the highest-voted answer to this post will be selected as that month's topic. Starting from today, users can propose their themes or topics. The selected answer will then be deleted to reduce clutter in the list.

After the selection, a new question will automatically be created in this format. An answer will then be posted to that question with links to all the posts in the featured topic in the fortnight.

We'll again keep a list of all the topics.

Happy Puzzling!

The first MTC will start on July 1st, 2022. In the meanwhile, topics will be gathered and voted on.

  • 3
    $\begingroup$ Is this event going ahead? (Asking for a friend...) $\endgroup$
    – Stiv
    Commented Jan 3, 2022 at 23:14
  • $\begingroup$ @Stiv Sorry all, wasn't able to be active here for 6 months. Sure, we could start in July if it's still relevant. Or perhaps a return of the chain puzzles? $\endgroup$ Commented Jun 15, 2022 at 18:44
  • $\begingroup$ Publicise it in TSL and I'm sure people would start contributing once others do. I think July works well for a starting time :) $\endgroup$
    – Stiv
    Commented Jun 15, 2022 at 19:09
  • $\begingroup$ How is this different from Fortnightly Topic Challenges? $\endgroup$
    – melfnt
    Commented Jul 9, 2022 at 7:13
  • 4
    $\begingroup$ @melfnt In no way other than its length. $\endgroup$ Commented Jul 9, 2022 at 7:15
  • $\begingroup$ @LukasRotter ok then, can I copy here some of the topics proposed for the last FTC that were not used due to the lack of activity? $\endgroup$
    – melfnt
    Commented Jul 9, 2022 at 8:50
  • $\begingroup$ @melfnt Sure, go ahead :) $\endgroup$ Commented Jul 9, 2022 at 8:52

9 Answers 9


- Current Topic -

Multi Puzzle — two (or more) puzzles in one

Create a single puzzle that has more than one valid solution, each arrived at in a completely different way.

e.g. Not a riddle that could have two potential solutions, but perhaps a riddle with a single solution, and another message hidden steganographically within the riddle.

Bonus points if the various answers to the puzzle combine somehow to either form a meta-answer or a final meta-puzzle.

This suggestion was inspired by the four Group 4 puzzles from the 2010 CISRA puzzle competition.


Stack Exchange crossover special

For this challenge, find a question listed in the Hot Network Questions ("HNQs") on the Stack Exchange network homepage, and use this as the inspiration or basis for a puzzle here on Puzzling. The only SE site ineligible for use in this challenge is Puzzling itself (otherwise it's not a crossover!).

To my knowledge, there are no overt whole-puzzle examples of this already on Puzzling, although oAlt has regularly used such posts within individual cryptic clues in the Cryptic Clue Chat Chain (CCCC) mini-game in The Sphinx's Lair (the site's main chat room). For example:

From Retrocomputing:
"Origin of string" making its second appearance (second!) (6) (link to chat)

Solution is SPRING ('Origin') by changing the second letter (t) of StRING to the second letter of aPpearance.

From Personal Finance & Money:
Make a mistake in Other Revenue (3) (link to chat)

Solution is ERR (Make a mistake), hidden in othER Revenue.

Idea inspired just now by finding "Older sister is taken and replaced with a mud golem" on Science Fiction & Fantasy, and wondering what a great story-based puzzle that might make...


Puzzles that could be in a video game

This is not a challenge for the tag (which, incidentally, has been an FTC), even though the tag may apply. The challenge is to make a puzzle which could conceivably appear as a minigame within a standard video game. Here is an example from Gaming SE.

Some restrictions are imposed by this premise, a notable one being a likely lack of instructions. That often causes problems for players when the puzzle's rules and/or goal lack enough clarity to allow for actual solving. A puzzle posted to here must of course not require random guessing in frustration (a common tactic some people I know will resort to when they just want to progress in their game).

The puzzle may be set in a generic video game or within a specific one, as you choose. But, it can't be something from a puzzle video game. The challenge is to design a functioning minigame puzzle.


Armchair geocaching


Geocaching is an outdoor recreational activity, in which participants use a GPS-enabled phone or similar portable device to hide and seek containers - called "caches" or "geocaches" - at specific locations marked by coordinates all over the world.

In many instances a geocache's specific coordinates are not posted in its listing, and instead they must be calculated from numerical information obtained in a scavenger hunt (a 'multi-cache') or derived by solving a puzzle (a 'mystery cache').

From the tag description

At the time of writing this, the tag is very much underused - only 10 occurrences. However, the concept of geocaching is something that sits incredibly nicely within the same wheelhouse as an appetite for puzzling, requiring the use of one's intuition, a keen eye, and the determination to see a quest through to its end. (And yes, full disclosure: I am an active geocacher myself...)

The 'multi-cache' and 'mystery cache' models mentioned in the tag description present an additional challenge to geocachers, requiring them to embark on a scavenger hunt for various numbers or solve a puzzle in order to extract the GPS coordinates where the physical cache container is hidden.

The purpose of this challenge would be to create a puzzle which ultimately leads to a specific real-life physical location - precisely defined by the geographic coordinate system (GCS) or an alternative established geocode system (like what3words), rather than merely hiding its name or related subjective information in a puzzle - without the need for the solver to visit it physically in real life!

Other complementary tags for this challenge might include , , and .

  • $\begingroup$ Example puzzle - admittedly one of mine... $\endgroup$
    – Stiv
    Commented Sep 8, 2023 at 15:06

Themed puzzles

This topic could be reused many times, with different themes — it might be something to keep in the back pocket for when there are no other topic suggestions.

Create a puzzle that adheres to a specific theme. These could be very broad, e.g.

  • Monkeys
  • Fireworks
  • Nanotechnology

They could related to a specific (well-known) franchise or work of fiction, e.g.

  • Harry Potter
  • Pokemon
  • FIFA
  • Sherlock Holmes

Or they could be much more specific (perhaps prompting a certain type of puzzle), e.g.

  • The bridge is out, but I need to cross!
  • The world just turned to black and white
  • Retracing my steps through the forest
  • First contact with an alien species
  • $\begingroup$ This is a very valid general suggestion; however, we'll need to make sure the bot doesn't pick this one up automatically and select it as the actual theme ("This month's theme is... er... themes, apparently!")! We'll need to have some other way of deciding which precise themes to use... Not sure exactly how to do that without just peppering this post with each one - possibly some kind of organised poll in chat? - but I'm sure we can work something out by the time it becomes relevant... $\endgroup$
    – Stiv
    Commented Sep 8, 2023 at 16:05

Locks and keys

In this challenge puzzles need to consist of a key and a lock.

The key needs to be solved in order to solve and/or make sense of the main part of the puzzle (lock).



Riddles to fit a provided answer

I'm not sure if I even think this is a good idea, but I'm putting it out there to see what others think...

There have been a few questions in the past that asked for riddles to fit a particular answer. I really enjoyed seeing the creativity used in creating some of the riddles and some of the out-of-the-box thinking employed.

Various Virtuosic Variety
the cleverest riddle whose answer is “river”
Riddles whose answer is "the moon"

That being said, some would argue that this site already has too many riddles, and encouraging more might be counterproductive.

In addition, this would preclude any challenge participants from solving other challenge submissions, since they would obviously already know the answer.

  • $\begingroup$ To be clear, the riddles fitting the answer would be posted as puzzles? I wouldn't want to encourage questions that ask for puzzle creation. $\endgroup$
    – bobble
    Commented Sep 8, 2023 at 17:47
  • $\begingroup$ @bobble Yes, it would be just like any other topic challenge. People would create questions and post them on the main site. The difference being that they would all have the same solution. $\endgroup$ Commented Sep 9, 2023 at 4:20
  • $\begingroup$ So a link to the MTC page might not make sense for those puzzles, since it would give away the answer. $\endgroup$ Commented Sep 9, 2023 at 4:21

Small ciphers

Unsure what others think about this, but still an idea. Also unsure whether or not this ties into the current topic, "2 or more puzzles in one"

Note: This is unlike Monthly Topic #14 because here, we wouldn't be thinking inside a very small box, instead, we are decoding a small cipher. However, there aren't really a lot of small ciphers, so while I doubt that this submission is going to go anywhere, it's still worth a shot.

Also, ciphers don't have to be large to be good! Some examples of good small ciphers would include:

  1. Cheese from Denmark by poco

  2. #cipherpuzzlesarecool by poco

  3. Numbers and Dashes by smlee

  4. My smol boi puzzle! :3 by CrSb0001 (sorry for shameful self-promo)

It is arguable that small ciphers are just not fun, since obviously, we aren't decoding that much to get to an answer, however, my argument comes from once again (sorry again for shameful self-promo), another puzzle of mine. This time being "A simple and quite fun cipher: Redux", which incorporates multiple layers into two parts in the puzzle, which really goes to show how much information can be decoded and still be a pretty small size. However, I would like to hear other people's opinions on this.


Red Herring-Centered Puzzles

All puzzles submitted must include at least one red herring, but preferably many. Even better might be to include many levels of red herring paths. Of course, creativity is desired, and imagination is your only boundary.

I'm not sure if this theme has already been done, and if so, maybe disregard this idea. If not, I think it could be really fun. Makes me wish that I already had a good red herring-themed puzzle, but I don't! But I will!


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .