The Sparkles the Unicorn game is only fun if you can find the beginning. To clarify the OP, it starts here:

https://winterbash2022.stackexchange.com/visit-sparkles

You can also join us in the Winter/Summer Bash 2022 chat room to discuss Sparkles' plight. (WARNING: Certain messages in the room may contain spoilers! You probably want to try to solve the riddles first, and only join if you're stuck to the point of it being no longer fun. Please do not post outright answers even in the chat room.)

Here's the full solution to the Sparkles adventure.

This is what you'd get from going to winterbash2022.stackexchange.com/visit-sparkles

It’s that time of year. Sparkles the Unicorn has been enjoying a year of bliss and vacation, and now it is time to fulfill her holiday duties to spread joy as far as it can go.

You walk to Sparkles’ house. As you move to press the doorbell, a note tacked to the door catches your eye. It reads:

BPM CVQKWZV UCAB ZMUIQV NZMM
AMJH OCZ XJMMPKODIB DIAGPZIXZ
WN BPM KWUXCBMZ.
FVB?
HP OZ YZE MPWTPGP JZF.
JR QB ABG ORYVRIR LBHE YVRF.
RZ YJ IJO WZGDZQZ TJPM OZMMDWGZ XDMXPDOMT.
UVY KV DL ILSPLCL FVB HYL VYNHUPJ PU UHABYL.
EM PIDM BISMV GWCZ CVQKWZV.
MNIFYH MJULEFYM ZLIG NBYCL BIGY.
XKGJ UAX TUZK, ROTK HE ROTK.
LHJO SPUL, H SLAALY. MYVT AOLT, H SVJHAPVU.
DGLB SQ. RUM UMPBQ, MLC NJYAC.
ACZGP ESLE JZF LCP SFXLY.

Sparkles is not home. Where did she go? Or… where was she taken…?

Again? Really? Can Stack Exchange not afford better security for Sparkles? I mean, I don't have this problem with my unicorn. Oh well. On with our giant captcha test quest to save Sparkles!

Based on the solutions from the 2021 quest, I took a stab at doing letter offsets, and it turned out the note was another offset puzzle, but with a twist: each line had a different offset. More importantly, it uses an "around the world" methodology (a Z with an offset of 5 becomes E). I wrote a simple PHP script to try different offsets ( https://3v4l.org has a real-time PHP parser so I could rapidly try different offsets). Insert any string into $string = ''; and change $offset (there's more than one place to use this)

<?php
$string = '';
$offset = 26;
foreach(str_split($string) as $char) {
    if($char == ' ' || $char == "\n" || $char == '.' || $char == '?' || $char == ',') {
        echo $char; continue;
    }
    $ord = ord($char);
    if($ord > (90 - $offset)) $ord -= 26;
    echo chr($ord + $offset);
} 

Each line gives a letter? Hmm... and none of the offsets are greater than 26. Let's turn the offsets into letters.

RERSOMESRFTSBO

Another puzzle! There's more than one word, so a mere anagram solver won't help much. It took some trial and error to weed out the next location

SOMBER FORTRESS

winterbash2022.stackexchange.com/somberfortress greeted you with this page

You arrive at the gate to a large, ancient fortress. The air is cold, and the stone walls are a dismal grey. You can see Sparkles beyond the gate, trapped once again. Sparkles sees you, and rushes towards the gate. The gate, however, holds firm.

On the wall next to the gate is an alphanumeric keypad with a small note taped to it. You're concerned for a moment that someone wrote the access code on the note. That'd be very poor security! But no, thankfully it just says /##£.

In front of you is a pressure plate, and a large leather knapsack sitting atop it. The bag is empty. You push the bag to the side, and stand on the plate. Glowing letters appear in the surface of the obsidian wall. They read:
SURELY A COMPUTER COULD NEVER SOLVE SUCH A PROBLEM.
THE WEIGHT’S THE KEY, YOU SEE.
AND COMPUTERS WEIGH NOTHING.

Seven stones fall from the ceiling around you, crashing into the floor below. You narrowly dodge these stones, and the dust takes a moment to settle.

Once the dust clears, you can see that the stones vary in their weights and sizes. On each stone is printed a set of letters. Each stone also fills the bag a specific amount. Thinking quickly, you pull your notepad out, and form the following table:

For the sake of brevity, I'm including the original table with the solution column added (i.e. Offset was not part of the original page, obviously)

Each of the scrambled words is POUNDS in a different offset. You can't make 100%, but you can make 99%. The hint is /##£(where £ is the UK symbol for pounds, the name of the UK currency), meaning the next URL is simple a two digit number, derived from adding the pounds from each stone in that 99%

3 (18%) + 11 (27%) + 13 (54%) = 27 (99%)

winterbash2022.stackexchange.com/27

At this point, you were asked a 10-question quiz. Some of the questions were quite arcane:

Q: What is the official name of the chat system?
A: Bonfire.

Get them all right and you save Sparkles! Otherwise... enjoy your secret robot internet (complete with secret robot mask).

Thank you.

Seeing this makes me happy.

bug status-completed

At some point in checking in on Sparkles, you need to know the number of SE moderators. This page claims that there are 539 moderators, but "539" is not an accepted answer (nor is "538" or "537" or "536").

Write-up

Note at Sparkles' house

Visiting winterbash2022.stackexchange.com/visit-sparkles reveals:

It's that time of year. Sparkles the Unicorn has been enjoying a year of bliss and vacation, and now it is time to fulfill her holiday duties to spread joy as far as it can go.

You walk to Sparkles' house. As you move to press the doorbell, a note tacked to the door catches your eye. It reads:

BPM CVQKWZV UCAB ZMUIQV NZMM
AMJH OCZ XJMMPKODIB DIAGPZIXZ
WN BPM KWUXCBMZ.
FVB?
HP OZ YZE MPWTPGP JZF.
JR QB ABG ORYVRIR LBHE YVRF.
RZ YJ IJO WZGDZQZ TJPM OZMMDWGZ XDMXPDOMT.
UVY KV DL ILSPLCL FVB HYL VYNHUPJ PU UHABYL.
EM PIDM BISMV GWCZ CVQKWZV.
MNIFYH MJULEFYM ZLIG NBYCL BIGY.
XKGJ UAX TUZK, ROTK HE ROTK.
LHJO SPUL, H SLAALY. MYVT AOLT, H SVJHAPVU.
DGLB SQ. RUM UMPBQ, MLC NJYAC.
ACZGP ESLE JZF LCP SFXLY.

Sparkles is not home. Where did she go? Or… where was she taken…?

Obviously, there is an encrypted message. From the source code of the website, you can get the following additional hint:

<!-- What *rotten* luck! Not only is Sparkles missing, but it looks like you'll have some unscrambling to do if you want to defend the unicorn. -->

"Rotten" is a hint for rot n a. k. a. Caesar cipher. You can use dcode.fr to decode the message. You will notice that each line uses its own key. Decoding each line reveals the following message:

THE UNICORN MUST REMAIN FREE
FROM THE CORRUPTING INFLUENCE
OF THE COMPUTER.
YOU?
WE DO NOT BELIEVE YOU.
WE DO NOT BELIEVE YOUR LIES.
WE DO NOT BELIEVE YOUR TERRIBLE CIRCUITRY.
NOR DO WE BELIEVE YOU ARE ORGANIC IN NATURE.
WE HAVE TAKEN YOUR UNICORN.
STOLEN SPARKLES FROM THEIR HOME.
READ OUR NOTE, LINE BY LINE.
EACH LINE, A LETTER. FROM THEM, A LOCATION.
FIND US. TWO WORDS, ONE PLACE.
PROVE THAT YOU ARE HUMAN.

And these are the keys for all lines (both directions):

The message tells you to derive one letter from each line and to create two words from them. But how?

There are no more hints, except: each line was decoded by a different key. The keys of a Caesar cipher will be in range of 1 to 25. So these keys can in turn be used to describe letters of the alphabet. And there is a name for that: Letter Number Code (A1Z26). You can use dcode.fr again to decode the numbers, which will give you:

• HUHGKMUGHTFGXK and
• RERSOMESRFTSBO for both key sets.

It looks like both decoded strings do not provide two words already. Strings, where the order of the letters has been scrambled, are called anagrams. And dcode.fr will help you again to decode the anagrams. From the second string, you will get SOMBER FORTRESS among other solutions, which is indeed the location you are looking for: winterbash2022.stackexchange.com/somber-fortress

To be honest, there is/was another way to get to this URL way quicker. Having a look at the web archive reveals that the above URL has already been crawled on 2022-12-23 and it is/was the only one that does/did not lead to hats and stuff.

Somber fortress

Visiting winterbash2022.stackexchange.com/somber-fortress reveals the next part of the challenge:

You arrive at the gate to a large, ancient fortress. The air is cold, and the stone walls are a dismal grey. You can see Sparkles beyond the gate, trapped once again. Sparkles sees you, and rushes towards the gate. The gate, however, holds firm.

On the wall next to the gate is an alphanumeric keypad with a small note taped to it. You're concerned for a moment that someone wrote the access code on the note. That'd be very poor security! But no, thankfully it just says /##£.

In front of you is a pressure plate, and a large leather knapsack sitting atop it. The bag is empty. You push the bag to the side, and stand on the plate. Glowing letters appear in the surface of the obsidian wall. They read:

SURELY A COMPUTER COULD NEVER SOLVE SUCH A PROBLEM.
THE WEIGHT'S THE KEY, YOU SEE.
AND COMPUTERS WEIGH NOTHING.

Seven stones fall from the ceiling around you, crashing into the floor below. You narrowly dodge these stones, and the dust takes a moment to settle.

Once the dust clears, you can see that the stones vary in their weights and sizes. On each stone is printed a set of letters. Each stone also fills the bag a specific amount. Thinking quickly, you pull your notepad out, and form the following table:

% of bag filled	Text on the stone
12%	ONTMCR
18%	MLRKAP
27%	EDJCSH
32%	LKQJZO
54%	CBHAQF
74%	UTZSIX
86%	QPVOET

From the note, you can derive that for the next link you will have to append something like /##£ to the URL. Furthermore, the challenge text says that there are stones that have a weight and a volume. The volume is given in the table, but not the weight. The texts on the stones all are Caesar ciphers of POUNDS. So you are probably looking for a weight. Going back to the note, remember that there is only an alphanumeric keypad. So it will not be possible to input £. As we are looking for a weight, lbs should be a valid replacement for £. So we are actually looking for a URL like /##lbs.

"THE WEIGHT'S THE KEY" suggests that there is a meaning in the Caesar keys again, like in the first riddle. And just assume what it says: The keys represent the weights of the stones. These are the keys/weights:

With the volumes given, you cannot fill the bag by 100%. So try to fill it as much as possible. Stones 2, 3 and 5 will fill it by 99%. The bag will then have a weight of 51 or 27, depending on the key set. And 27 seems to be the correct answer.

Another way to get to the URL is to use brute force. The following PowerShell snippet will give you the correct URL in seconds:

10..99 | ForEach-Object {
    $url = "https://winterbash2022.stackexchange.com/$($_)lbs"
    try {
        $a = Invoke-WebRequest -Uri $url -UseBasicParsing
        Write-Host "$url" -ForegroundColor Green
    } catch {}
}

Result: winterbash2022.stackexchange.com/27lbs

Quiz

Visiting winterbash2022.stackexchange.com/27lbs reveals the final part of the challenge, the quiz:

There she is! You have are almost there!

Can you help lead the unicorn to safety, and earn the vaunted Defender of the Unicorn hat? To do so, you must answer 10 questions correctly, with the following stipulations:

• All answers are either integers or at most two words (no punctuation, spaces optional), case insensitive
• All answers are discoverable through Stack Overflow/Stack Exchange sites/blogs
• If you get a question wrong, you will have a one minute timeout before you can attempt another answer
• If you get three questions wrong, Sparkles will strike out on her own
• Your progress will reset after two hours of inactivity
• Please do not share answers to questions with others before January 4, 2023 at 21:00 UTC.
• The Defender of the Unicorn hat will only be awarded on Meta Stack Exchange. If you do not have an MSE user, you are welcome to go through the quest, but you will not be awarded the hat.
• GL,HF!

To finish the challenge, you have to answer 10 random questions from a question pool. Some of the questions are:

• What is the name of the design system created and maintained by Stack Exchange?

  Stacks

• How many inductees does the Stack Exchange Security Hall of Fame have?

  29

• What was the name of the event in 2011 that eventually became Winter/Summer Bash?

  Hat Dash

• What unofficial term is used to describe the act of mindlessly completing reviews without regard to the post's actual quality?

  robo-reviewing

• What's the official name of the chat system used on the Stack Exchange network?

  Bonfire

• How many (non-employee) moderators (unique accounts) moderate the network?

  539

• What is the maximum amount of reputation someone can earn by suggesting edits?

  1000

• How many active network sites are there as of December 2022?

  180

• What tag had the most questions asked on Stack Overflow in 2022?

  python

• In what year was the highest-scoring Artificial Intelligence question asked?

  2016

• What feature got a major upgrade and rename this year?

  Saves
  ["Bookmarks" was also accepted as an answer here]

• What tool did people use to answer large numbers of questions in December 2022?

  ChatGPT

• What site did we bid farewell to this year?

  Windows Phone

• What is the name of the staging zone where new Stack Exchange sites can be proposed?

  Area 51

• How many users total across the Stack Exchange network have at least 1 million reputation on a single site?

  8

• What is the highest reputation required on any site to create new tags?

  1500

• Which site was most recently added to the Stack Exchange network?

  Solana

Thanks to the powerful magic of online anagram solvers, almost no one actually noticed that the solution to the first riddle in this game actually had at least two valid solutions.

The string "RERSOMESRFTSBO", obtained from the rot crypt offsets used when decoding the various lines of the first message does not only anagram to SOMBER FORTRESS...

Indeed, a more archaic answer is "SOMBRER FOREST". Should you try to walk this alternate path...

you would end up with a desperate attempt (courtesy of Slate apparently) to make you realize that you are chasing the wrong white rabbit. I assume that the explicit mentioning of a "castle" is an attempt to make you think of a "fortress"...

But all it did for me was making me think of Super Mario and my old "Your Answer is in another castle post". So... I ended up wasting too much time looking for a riddle on the wrong page before trying the other answer.

Update: thanks to Slate for sending this in. Actually they made a version for SORBETS FORMERS too...

bug status-completed

When your visit to Sparkles is successful, you receive the message:

You have been awarded the Defender of the Unicorn hat, wear it with pride!

However, the text "Defender of the Unicorn" in the message is linked to the 2021 WB page instead of the 2022 one!

feature-request status-deferred

Can the error message for not being logged in change from

Please log in to participate

to

Please log in to https://winterbash2022.stackexchange.com/ to participate

It's a bit confusing. I spent a good ten minutes making sure that I was logged into the Stack Exchange and Stack Overflow sites, only to realize I also needed to log into the Winter Bash site separately.

If you pass the quiz, you get the message:

But if you fail you get:

Note: If you pass without fail, you don't recieve "Yes, a Robot" hat. Luckily, you can go back to the quiz and fail. Enjoy your failure.

feature-request status-deferred

Disallow web crawlers on the challenge sites. Possible solutions:

• Modify robots.txt "accordingly"
• Use Basic Authentication for the challenge sites (this would really enforce it)

Currently, it is quite easy to skip some riddles by checking the results of publicly available crawlers.

Rescuing Sparkles the Unicorn, again

So, get this: after getting Sparkles the Unicorn out of trouble last year, I was looking forward to visiting her this year. I'm sure you can imagine my shock when she wasn't home: when I got to her house, there was a note taped to her door. Now my pleasant visit turned into a rescue mission!

/visit-sparkles

The first stage of the puzzle is at /visit-sparkles.

BPM CVQKWZV UCAB ZMUIQV NZMM

AMJH OCZ XJMMPKODIB DIAGPZIXZ

WN BPM KWUXCBMZ.

FVB?

HP OZ YZE MPWTPGP JZF.

JR QB ABG ORYVRIR LBHE YVRF.

RZ YJ IJO WZGDZQZ TJPM OZMMDWGZ XDMXPDOMT.

UVY KV DL ILSPLCL FVB HYL VYNHUPJ PU UHABYL.

EM PIDM BISMV GWCZ CVQKWZV.

MNIFYH MJULEFYM ZLIG NBYCL BIGY.

XKGJ UAX TUZK, ROTK HE ROTK.

LHJO SPUL, H SLAALY. MYVT AOLT, H SVJHAPVU.

DGLB SQ. RUM UMPBQ, MLC NJYAC.

ACZGP ESLE JZF LCP SFXLY.

Each line is encoded using a Caesar cipher with a different amount of rotation for each line. I worked out each line and what the letter offset is (using CyberChef):

Each offset represents a letter of the alphabet. Taking the nth letter of the alphabet for each offset, n, gives rersomesrftsbo. That can be unscrambled to the phrase "somber fortress" (thanks anagram finder website!).

/somber-fortress

(or /fortress-somber, the order doesn't matter)

Here we get the next stage of the puzzle.

You arrive at the gate to a large, ancient fortress. The air is cold, and the stone walls are a dismal grey. You can see Sparkles beyond the gate, trapped once again. Sparkles sees you, and rushes towards the gate. The gate, however, holds firm.

On the wall next to the gate is an alphanumeric keypad with a small note taped to it. You're concerned for a moment that someone wrote the access code on the note. That'd be very > poor security! But no, thankfully it just says /##£.

In front of you is a pressure plate, and a large leather knapsack sitting atop it. The bag is empty. You push the bag to the side, and stand on the plate. Glowing letters appear in the surface of the obsidian wall. They read:

SURELY A COMPUTER COULD NEVER SOLVE SUCH A PROBLEM.

THE WEIGHT’S THE KEY, YOU SEE.

AND COMPUTERS WEIGH NOTHING.

Seven stones fall from the ceiling around you, crashing into the floor below. You narrowly dodge these stones, and the dust takes a moment to settle.

Once the dust clears, you can see that the stones vary in their weights and sizes. On each stone is printed a set of letters. Each stone also fills the bag a specific amount. Thinking quickly, you pull your notepad out, and form the following table:

% of bag filled	Text on the stone
12%	ONTMCR
18%	MLRKAP
27%	EDJCSH
32%	LKQJZO
54%	CBHAQF
74%	UTZSIX
86%	QPVOET

The proper way to solve this

All of the texts on the stones are the word POUNDS with different amount of letter rotations:

The offset value is treated as the weight of the stone in pounds for this puzzle.

Here's what we need to figure out: we need to fill up our knapsack with stones to make it as heavy as possible, keeping in mind that we can't overfill the bag. This is a form of knapsack problem.

The optimal solution is to put the 2 pound and 25 pound stones in our bag. Combined they take up 98% of our bag and weigh 27 pounds.

The puzzle text says that we need to enter a code into "an alphanumeric keypad", so we know the next URL to go to is all digits. Since the sticky note says /##£ (£ is the currency symbol for British pounds), we know to get to /27 next.

The cheaty way to solve this

Just try all numbers from 0-100. I wrote a script to try all possible numbers, but it wouldn't be to hard to do this manually.

/27

The final stage is a quiz with 10 questions, randomly selected from a pool. Here are all possible questions and their answers:

feature-request status-completed: Auto-focus the answer input in the Unicorn Quiz.

Because it kills me to move my mouse or press the tab-key once /s