# C equals O, but in general

You find yourself trapped in a room, facing a wall where all information is located. There is also a table, on it a permanent marker.

Before inspecting every piece of info, you focus on the door. You observe that on the door is a lock that needs a word of length eight letters.

You turn your attention to the leftmost part of the wall, and see a grid with all the letters of the English alphabet, with a few symbols for some reason.

To its right is another grid, with dots, numbers, and letters...

You then look at a third grid. This one is much larger, and is mainly occupying the center of the room.

You notice that there is a list of instructions below this large grid.

1. You must start at the sun tile.
2. Valid move directions are north, south, east, and west.
3. In a move, you cannot deviate from the row or column you are currently in, depending on whether you move east/west or north/south, respectively. In other words, the move you make must be completely straight. For instance, if I am in a 3x3 tiled grid with columns 1, 2, and 3 from left to right and rows A, B, and C from top to bottom, and I am in tile 2A, and my move, which is southward, allows me to reach the bottom of the grid, then the only valid place I can end up on is tile 2C, and not tiles 1C or 3C.
4. No backtracking. The direction of your (n+1)th move cannot be the reverse of the direction of your nth move. If I move eastward, my next move cannot be westward, and vice versa. If I move northward, my next move cannot be southward, and vice versa.
5. Any tile can only be visited at most once. For instance, when the start of your move is at tile A and the end of it is at tile E, and tiles B, C, and D are between A and E, you can never visit A anymore, but you can still visit B, C, and D. If you move away from E, you cannot visit E anymore, and so on.
6. A valid move also consists of not skipping over walls (tiles colored black).

Those are some lengthy guidelines. You look to the right of the large grid, and there an illustration is placed. It has some stars and... 4's and 2's?

You finally reach the rightmost part of the wall, and you see quite a number of notes.

The first notes you encounter are two similar-looking ones.

CCW S OI SJPF PDDM HW YP MFN*
CW N PAY WAX FIGHTS

The next note you see has a poem on it.

$$\\\rm{\textit{1's and O's}}\ \$$

I'm wondering where my life should go;
Direction, the next, I have not known.
Gaining hope, though, doubtless is worth doing;
Most of all, loving each other's assuring.

Yet another note after that:

Lydian x 2

And you read off the last note, having reached it:

c equals o, but in general

??? The hell could that mean? What do any of these mean?

You step back, having absorbed a lot of information. Your eyes dart back to the door lock, reminding you of your desire to escape. After all, even though you would love to be trapped in a room filled with puzzles, you wouldn't want to stay there for eternity, right?

...Right?

Suddenly, you hear a voice, which fills the whole room. "Though I am the one who trapped you," they say, "I will not hesitate to give you a hint every ~24 hours." ...Weird experience, but you're not complaining.

Hint 1.

You have finished solving the slitherlink puzzle. You see that there are words contained inside the loop. Involuntarily, you make a mental note of the number of letters, and... wait, have you seen this before...

Hint 2. (replaced)

NOTE: The previous Hint 2 was worded wrongly. In lieu of that, I shall be giving a new Hint 2. Greatly apologize for this.

Deusovi was on the right track about the "orientation and starting point".

Hint 3.

For the similar notes, which are encrypted, the first specification implies rotation.

The second specification is always the same for each (8n-7)th letter, where n is an integer greater than zero.

(...and don't forget the marker.)

Hint 4.

(Interesting to see that no one else has cracked this yet :D)

If nothing is specified, then by itself an encrypted letter or symbol has eight possible decryptions.

Hint 5.

Not surprisingly, the title of the poem is intentional.

Hint 6.

We shall now tie everything together.

Indeed, the poem works that way. But what would be the simplest way to parse such extracted information?

Moreover, one will hopefully realize that "C equals O, but in general" itself does not clue a letter, but rather narrows down options for one. For now, I choose not to put further details about that here and instead put them in the next hint.

Hint 7.

There is no ASCII nor alteration. There are four substeps to get from the poem itself to the letter, and Reinier has gotten the first one so far.

Hint 8.

I'm almost running out of hint ideas, but I will try my best not to xD

Echoing Hint 6, how else can one interpret binary?

Hint 9.

Jens has continued where Reinier got stuck. However, since Jens got stuck as well and is really close to getting the seventh letter, I will not hesitate to say that "SC" should remain written as "Sc"; hopefully it helps to retain the case.

• Disclaimer: I have not gauged how difficult or easy this may be. That aside, I was entertained and amazed by a lot of medium-/large-scale puzzles on this site. Hopefully I can somehow return the favor. – oAlt May 2 '20 at 7:36
• (EDIT: I have not noticed at first that the image of the third grid was missing its top row. Fortunately, it has been fixed now.) – oAlt May 2 '20 at 15:13
• (ANOTHER EDIT: There was a missing character in one of the notes. Apologies; this will be my last edit pertaining to correcting a mistake in the puzzle :(( – oAlt May 5 '20 at 7:30
• Is the tag "Anagram" also relevant? – Jens May 11 '20 at 21:03
• @Jens indeed, it is :) – oAlt May 12 '20 at 1:51

NB I had originally just deduced the final 2 missing letters and the passcode, but since this answer was awarded the green checkmark by the OP for completing the puzzle I am editing in sufficient detail to make this a complete answer. Please note that @Reinier did most of the heavy lifting (5 letters) and @Deusovi contributed significantly too (1 letter and guidance to @Reinier in comments) - please consider upvoting their answers...

Alphabet grid (Letters 1 & 2) solved by @Reinier:

This, in combination with the two notes reading "CCW S OI SJPF PDDM HW YP MFN*" and "CW N PAY WAX FIGHTS" yields up two things - a message "TO TAKE THIS IS TO LOSE", which clues the letter L, and a series of symbols that must be marked on the grid to form the shape of a letter C:

See @Reinier's answer for the solution path.

Slitherlink (Letter 3) solved by @Deusovi:

The solved Slitherlink puzzle reveals a path in the shape of a letter R - see @Deusovi's answer for the solution, reproduced here:

Stars, 4's and 2's (Letters 4 & 5) solved by @Reinier:

The Slitherlink also reveals an additional hidden message enclosed within its loop: "VINE RING DIES RATE SONS LO". These are related to the puzzle involving the stars, which indicates we need to find 2 letters that can precede each of these words to make new words - these are BO.

Letter grid with sun tile (Letter 6) solved by @Reinier:

We can interpret the note 'Lydian x2' to mean that we need to find a path in the grid following a particular pattern - again, see @Reinier's answer for the full solution. Ultimately, (once you ignore all the false trails which look like they will begin with 'BINARY' or 'MORSE'!) the coded message this reveals is 'FOURFORTYHERTZ', which is the frequency of an A note in music:

"1's and O's" poem (Letter 7) solved by @Stiv with assist from @Reinier and @Jens:

@Reinier realised that the poem could be translated into binary numbers by translating words containing the letter 'o' to 0, and without it to 1. This gave the binary numbers 1011100, 0111100, 1000100 and 0010101.

@Jens then realised (in comments) that these binary numbers translate into decimal as 92, 60, 68 and 21, and that the chemical elements with these atomic numbers in the Periodic Table have the symbols U, Nd, Er and Sc.

My own contribution was to realise that this spells out UNDER Sc, and that the element beneath ('under') Scandium (Sc) in the table is Yttrium, which has the symbol Y - this is the seventh letter.

The 8th letter and final passcode - solved by @Stiv:

We then have seven letters identified and one question mark remaining:

LCRBOAY?

Two candidates for a final answer brought about via an anagram sprang to mind:

CARBONYL (requiring 'N') and CARBOXYL (requiring 'X').

The last remaining unused clue "c equals o, but in general" helps us work out which one of these is correct...

Noting that this message can be written as C=O, we need to notice that this looks like a double bond between a carbon atom and an oxygen atom in scientific 'structural formula' diagrams.

CHEMISTRY WARNING! In this situation the carbon atom can be attached to 2 other atoms also (since a carbon atom has 4 unpaired electrons to make 4 bonds). When you have a carboxyl group, one of these bonds always attaches the carbon atom to a 'hydroxyl group' (an oxygen atom bonded to a hydrogen atom: -OH). However, in the more general case where we do not specifically identify what else is attached to the carbon atom, this atomic arrangement is known as a carbonyl group:

Using the 'in general' component of this last clue to realise the OP is intending us to use this general case, we can deduce that the eighth letter should be N, so that if we rearrange all of the letters we've found the passcode to type must be CARBONYL!

As I say at the top, big credit to @Reinier for the bulk of the work. In sporting terms, they ran from their own half, dribbled past all of the defenders and then just squared the ball to me to tap into the unguarded net. I may have scored the goal but there's no doubt who's truly responsible for making it happen...

• @oAlt Yes, I spotted there were two potentials with that one missing, and exactly like you say I used the 'in general' to help narrow that down! :) – Stiv May 12 '20 at 7:50
• I will mark this as the accepted answer, since you were the first one to arrive at the password. However, to everyone else, I strongly urge y'all to upvote not only this answer, but also Deusovi's and Reinier's too. :D – oAlt May 12 '20 at 7:51
• @oAlt Aha, I see. In which case I will edit this answer for completeness in around an hour when I will next have a moment! – Stiv May 12 '20 at 7:53
• Oops! Thanks @oAlt for that spot! – Stiv May 12 '20 at 10:39
• Congrats on solving! And also thanks to @oAlt of course for providing the great puzzle! – Reinier May 13 '20 at 15:03

## Alphabet grid

This grid should be combined with the two similar notes:
CCW S OI SJPF PDDM HW YP MFN*
CW N PAY WAX FIGHTS
For the first note, the first four letters indicate "Counterclockwise South" (as found by Deusovi), which yields (as indicated by all the hints) a starting direction and a rotation. To decrypt the rest of the note (OI SJPF PDDM HW YP MFN*), we start with replacing the O by the letter in the grid below it (T), then we rotate the direction one step counterclockwise to get SE, then we replace I by the letter to in the SE direction (O), we rotate the direction again to get W, et cetera.

This gives

TO TAKE THIS IS TO LOSE
As indicated in the comments by Deusovi, this probably clues the letter L. The second note decrypts to
K+U *F- JCBDPY
This seems to make no sense at all.

However, we can do the following:

We grab our marker, and mark all characters on the grid which occur in this second decrypted message. The result is:

This clearly shows the letter C.

## Large grid with instructions

Here we use the note "Lydian x 2". According to Wikipedia:

"The modern Lydian mode is a seven-tone musical scale formed from a rising pattern of pitches comprising three whole tones, a semitone, two more whole tones, and a final semitone."

So this Lydian mode gives us a sequences of whole tones and semitones, and Lydian x 2 suggests the following sequence:
1 1 1 1/2 1 1 1/2 1 1 1 1/2 1 1
Now below the large grid, there is also a note about the meaning of "1" and "1/2", in particular it gives us a way to link these two numbers to step sizes for the puzzle. So apparently we want to find a path through this grid which satisfies all stated rules, and has step sizes corresponding to "Lydian x 2" as stated above.

I found only one way of doing this (but this was before the top row was added):

We note that the visited cells spell "FOURFOURTYHERTZ". According to Wikipedia, this corresponds to the note A in music.

## Stars, 4's and 2's

As already found by Deusovi, the slitherlink yields the words VINE RING DIES RATE SONS LO. So we get 5 words of length 4, and 1 word of length 2. Now there is another place where we encountered five 4's and one 2: namely in the figure with the stars. I think this figure should be interpreted in the following way: the star resembles 2 letters (indicated by "star = 2"), and when we put these two letters before each of the other words, we should get 6 new words.

The best fit I found was:

BO, to give the words BOVINE, BORING, BODIES, BORATE, BOSONS and BOLO. So this would make the letters for this part of the puzzle "BO".

## The poem

The title of the poem suggest that we might have to do something with binary. Furthermore, each line contains exactly 7 words, this probably isn't a coincidence. So we somehow want to convert each word to a binary digit. Now we notice that the title of the poem is "1's and O's", note that the "O" here is a letter, not a digit. This suggest that perhaps the words of the poem that contain an O correspond to zeros, and the other words are ones. So we get the following binary numbers:
1011100
0111100
1000100
0010101
Using ASCII to translate this yields \<D[NAK], so I guess we need to do something differently...

If we however proceed to

reverse the binary strings, and flip every bit, we get
1100010
1100001
1101110
0101011
This translates to ban+, which still does not make a lot of sense. If we however flip the first bit of the fourth number (the only reason I do this is since it makes it into a letter, there is not motivation for this from the puzzle itself, as far as I can see), it translates to bank. So maybe, this poem should give us the word bank, or an abbreviation of this. (But I am not too certain whether this is the intended solution.) So possibly this poem just gives us the letter B.

## Some final notes

- The letters found until now are "LCRABOB". To me this does not seem to be a part of some word, so maybe the order of the letters should be changed.
- The only unused clue at this point is the note "c equals o, but in general". I am not sure what to do with this, maybe it is some kind of cryptic clue?

• "TO TAKE THIS IS TO LOSE" -- "take an L" is a common phrase meaning "lose". So that one's probably cluing the letter L. – Deusovi May 6 '20 at 14:00
• @Deusovi, that indeed makes sense, I edited into my answer. – Reinier May 7 '20 at 11:46
• @oAlt I am not surprised that the actual solution should be simpler than this. I guess I will keep thinking about it for a while... – Reinier May 7 '20 at 12:12
• Rot13( Vs gur ovanel ahzoref ner pbairegrq gb qrpvzny, jr trg 92, 60, 68, 21. Vagrecergvat gurfr nf ngbzvp ahzoref jr trg gur ryrzragf "H Aq Re Fp" be "Haqre FP". Abg fher jung gb znxr bs guvf. Ubjrire, gurer ner gjb bpphenaprf bs FP va gur ynetr tevq, bar ubevmbagny naq bar iregvpny. Creuncf gung'f eryrinag.) – Jens May 10 '20 at 12:10
• To continue from @Jens... rot13(Va gur Crevbqvp Gnoyr, L (Lggevhz) vf qverpgyl haqre Fp (Fpnaqvhz) - V guvax gur yrggre lbh arrq vf L...) – Stiv May 11 '20 at 18:43

The dotted grid

is a Slitherlink puzzle. Its solution is below:

It appears that the puzzle gives a message:

The loop makes an R shape. Additionally, the letters inside the loop, starting at the bottom left, spell VINE RING DIES RATE SONS LO (or perhaps RATES ON SLO).

Thoughts on the rest of the puzzle:

The first grid is demonstrating both a layout for the alphabet, and a grid that "wraps around". I'm not sure what use this has - perhaps as a way to decode offsets into letters (though we'd need a given starting point).

The navigation grid seems to be something we need to "navigate" in, based on the instructions. It's possible that we can only take steps of size 2 or 3 (as shown below the grid), and we're supposed to spell out words. If this is the case, the stars may be giving total point scores for each word. Unfortunately, after a fair bit of effort I haven't gotten anywhere with this.
I've also attempted solving the same grid as a tilt maze (where you must keep moving until you hit a wall). Haven't been able to spell out a message that way either.

In the first two notes, CCW S OI SJPF PDDM HW YP MFN and CW N PAY WAX FIGHTS, the first two "words" of each note are likely "counterclockwise south" and "clockwise north". This may give an orientation and a starting point? I'm not sure what to do with this information, though. I've tried spelling these with the navigation grid, but had no luck.
It's also possible that the remainder of each note is enciphered somehow: this seems likely based on the letter patterns. I've attempted to break this as a simple substitution cipher, but nothing has come of it -- I assume the way to decode this comes from some other part of the puzzle.

I'm not sure about the other three parts. "Lydian" likely refers to the Lydian mode in music, but I don't see how that could be applied to the puzzle.

• I normally wouldn't answer with this little progress, but it's been nearly 12 hours and nobody else has gotten anywhere. And since OP was unsure about how approachable it was, I figured I'd give my thoughts so far. (If anyone thinks this would be more appropriate as a CW answer, let me know - I'd be happy to change it.) – Deusovi May 2 '20 at 19:04
• Upvoted, since you got one letter already :0 Those are nice insights as well. You may want to continue considering which note/s goes with which grid/s, and which note/s stands on their own. – oAlt May 3 '20 at 1:32