Recognizing a Metapuzzle

Creator's note: This puzzle was meant to be released in April 2017 for the fortnightly topic challenge. As you can see, it is currently over a year late. Real-life events interfered, and the scale of the project kept growing. It's finally out now, though, so I hope you enjoy!

Metapuzzles are sneaky. They hide in the shadows, seeming to be final yet hiding more.

Sure, some metas (like ffao's "Party for Hope", Rubio's "I, for one...", and my own "Chess Fortnight") are fairly apparent (even if not easy). But others (like Sp3000's "archived metapuzzle?" and Wen1now's "Parallelisation") can lay unnoticed for weeks, or even months!

I feel that a solution exists, though - and it's hidden just beyond these 29 metapuzzles. I've already solved the base-level puzzles, so I just need your help for the rest.These 29 puzzles hide something that would help us notice these metapuzzles at a glance: What do we need to recognize metapuzzles as soon as we see them?

STONE
CRUISE
MR. T
WEAVER
ZETA
EINSTEIN
DILLON
HOPE
FOSTER
GRANT

2

ARCTURUS MENGSK
A CAPELLA
URI GELLER
UNICURSAL
PROFESSIONAL GOLFERS' ASSOCIATION
SAVIOR

REVOLVING
PARASITE
WILD DUCK
HIBERNATOR
MULTIPLYING
HEEL
HUMMING
TRASH BAG
CAVALRY
TRANSFORM

FROGS
HEIGHTS
DIRT
BULLETS
HEAVEN
DARKNESS
ENCLOSURES
THIRTEEN
DOCTORS
SNAKES
URINE
MIRRORS

5

BIRDS BARBERSHOP
CLIFFORD ALGEBRA
COLOR SPECTRUM
EARTH DIVER
HINDU GOD
INDUCTION COIL
IRON FILING
LIGHT WAVES
NARRATIVE ANALYSIS
PROFESSIONAL ASSOCIATIONS
SPECIALIST KNOWLEDGE

6

COMMUNIST
DEMOCRATIC CENTRALISM
LED APPLE
MORTON SOBELL
OPERATION LITTLE SWITCH
ROOSEVELT
SEE IT NOW
TAHA'A
TAILGUNNER
TERRY MELCHER

7

FINISHED
FAR EAST MOVEMENT
DESTINY
STEAK SAUCE
DATA VISUALIZATION
TRITIUM
GAMING CONVENTION
MISSING
CUBE
SEARCH
EXPLOSIVE
LOGORAMA

REAL
VOUS
HIPE
HIPS
POUR
SEXY
TYVM
SPXU

REVERED
WORSE
PIOUS
FURY
ANEMONE
POLICE
ALBEIT
VIAL
ALLOWED

10

ACCOUNTANT
ATOMIC AGE
BEIJING OLYMPIC GAMES
CLEANSING AGENT
COMMUNICATION
CONDENSED MATTER PHYSICS
ENGAGEMENT RING
ENGLISH CHESS NOTATION
FLOWERING TOBACCO
GM_FLATGRASS
I'D RATHER EAT GLASS
MIKE VANDERJAGT
RENAULT G-TYPE
SCATHING REMARK

11

CHEAT
CURRENT DOLLAR
FAIRLY ODD PARENTS
GEOHASHING
HEALTHCARE TOURISM
SHEBANG
STARTLING
TWENTIETH PERCENTILE
WITHSTAND

AFTER DARK
NOVICE
STARTUP
WEST END

STRIDE
LIFTING
THE RIG
TURF WAR
PIGSKIN
STARSHIP TITANIC
AIRBALL
SCAVAGE
ESCHATON
DESCENDANTS
NICHIJOU
JEAN ARP
TOP SECRET

AL CAPONE
BONNIE AND CLYDE
DOC BROWN
ELVIS PRESLEY
GOKU
WALTER WHITE
WRIGHT BROTHERS

15

APPLIED ANATOMY
BAR BILLIARDS
CHRISTOPHER COLUMBUS
EON
EXPERT EVIDENCE
GIVE GROUND
HARMONY HAMILTON
MILWAUKEE MILE
PRECLINICAL PHASE
STANDING START
¡VIVA! VAUGHAN
WARM WATERS

ACTIVITY
ANNOUNCE
ARRAIGNS
ASTONISH
BEHEMOTH
BIRTHDAY
CATEGORY
INDIRECT
JEREMIAH
MEDIOCRE
OPTIMISM
ORATORIO
OTIOSITY
REASSESS
SCENARIO
STRANGER
THOUGHTS
WRENCHED

TERM WORK
IMMUNITY
SERMON
VINEGAR
CAVERN
ENGRAIL

ASSESS
CALORY
GYROSE
POIROT
TRILLS
TROATS
FONDLE
NEEDLES
SHILOVSKY
SPUR
THREE-WHEELERS
VEGETABLE

FOG
RELAX
ANGRY
COMMERCIAL
DONKEY
CAMBRIDGE
ELECTRON
AIRPORT
HILLBILLY
ICON
ETIQUETTE
BANG
INFLUENZA

ITEM
REVERE
FILER
SHARIZ
SWAMI
ABODE
NEPAL
ÜBUNG
WRAP
RARER
LYSYL
IOUS
LAPEL
HULU
APPTIX

21

CHALK TIRES
COUNTERCLOCKWISE REVERSIBILITY
HUMOR ESSAYS
KISS-ASS
MANEUVER UNDER FIRE
SEARCH ENGINE OPTIMIZATION
TWI-MOM
WISH FULFILLMENT THEORY
WOOLEN SHROUDS

AARDVARK
BRAVEST WARRIORS
GRUMMAN
HALF LIFE
PET PEEVE
SOCKPUPPET

GAELIC
NARROW
CAPED
DOLL
CATNAP
RUB
JIMBO
SAME
PAISLEY
NICELY
BASAL
LINGER

24

BORINGHAM
COINCIDED
EARTHSYNC
ORBIT
SAUCER WITH HANDLE
SHALOM
TIRED
WOOD HOOPOE
YULE BALL

25

MEDIATOR
INSULT
WIFEBEATER
CRUX
GINGER
EVENING TELEVISION
EYEWITNESS
PAROUSIA
POWER ON
TORTURE
DESPERATE
INCISORS

ASS
BIT
FLIT
GRAILS
IMP
ISH
SERIF

MINI
ENACT
OH
FLUE
BORED
COMPLETION
TRIO
EROTIC

AMPS
ARRAY
ARROW
DOWN
FANG
GROTTO
MBIRA
NICHED
PRIORS
SAHARA
SASS
YETIS

LUMP
ROUSE
AMBLE
EVILS
PRAISE
TURNS
PIKE

Bits and Pieces

(For larger versions of most of these images, you can click them and remove the m just before .png in the URL. This shouldn't be necessary for anything other than visual clarity.)

CTVEDEMER
YEROWEPUT
SVACHVIEQ
MELNEAROC
ILIDVTCNR
HTCKELSIU
STETSCUCS
VEXEAHTIA
ULSDEIEFG
EEVHSHDLE

DLERCZAPSLMND

Bach

No answer here has more than two words.

avatar, coin, figures, pack

• wowww, I get nothing!! – Preet May 2 '18 at 2:07
• I’ve been waiting all my life for this. – TheGreatEscaper May 2 '18 at 5:51
• im just going to skip this one i think :ok_hand: – L_Church May 2 '18 at 10:37
• Errata so far: 8's answer list was modified, 16 and 21 were realphabetized, one arrow was flipped in the 6×8 grid, one arrow was modified in the colored arrow grid, and the 13-letter string was changed slightly. – Deusovi May 5 '18 at 16:44

1

Surnames (or portions thereof) of famous actors (mostly)
STONE = Emma Stone (1)
CRUISE = Tom Cruise (1)
MR. T = Laurence Tureaud (2)
WEAVER = Sigourney Weaver (2)
ZETA = Catherine Zeta-Jones (2)
EINSTEIN = Albert Einstein (3)
DILLON = Matt Dillon (1)
HOPE = Bob Hope (2)
FOSTER = Jodie Foster (2)
GRANT = Hugh Grant (2)

Find each one's Bacon number. (Einstein's Bacon number is 3, largely due to a credited appearance in Champagne for Caesar in 1950.)
Index into answer by Bacon number to get SCREEN DOOR, with the non-decreasing sequences separating the words.

13

This meta was solved after the tag list was identified; this is the sports meta. This meta uses the image of the thirteen left-/right-facing chevrons.
Each answer is either a fictional sport or game, or a story/person that has described a fictional sport or game. This chevrons indicate, in order, which of the two options each answer is: if the chevron point right, then the answer is a sport or game, and we need to identify the story; if the chevron points left, then the answer is a story or person, and we need to identify the sport.
Most of these sports/stories can be found on either the TV Tropes page for Fictional Sports, or the Wikipedia list of fictional games.
STRIDE is a parkour-like sport> in the Prince of Stride game.
LIFTING is a surfing-like sport> in the game Eureka Seven.
THE RIG is a story by John Ducie which describes the violent sport of Rigball, with sufficiently weird rules that I can't describe it as (real sport)-life.
TURF WAR is a mode in the video game Splatoon and its sequel, in which inklinks must cover as much of the ground in their own colour ink as they can.
PIGSKIN is an American-football-like sport (plus that whole magic thing) in On a Pale Horse.
STARSHIP TITANIC (based on Douglas Adams' Hitchhiker's Guide trilogy) references a sport called Nib.
AIRBALL is a sport in a couple media, though my favourite/arguably the most famous/the one required here are all the same: Avatar: The Last Airbender.
SCAVAGE is a sport in the series of books called The Liaden Universe.
ESCHATON comes from David Foster Wallace's Infinite Jest.
DESCENDANTS is a Disney Channel Original Movie all about the children of famous Disney protagonists and villains, and includes a sport called Tourney.
NICHIJOU includes an individual sport called Igo Soccer.
JEAN ARP, the Dadaist artist, describes the team sport of Eggboard, in which both teams leave.
TOP SECRET! describes the sport of Skeet Surfing.

In order, take the first letter (ignoring leading 'The's) of the halves that we had to identify, to get the answer, PERSONALITIES.

18

This meta uses both 6 by 6 grid pictures.
Answers are in two separate alphabetical lists. The answers in the second half have synonyms/suggested words that match the answers in the first half, except with CAR taking the place of two or three letters.
FONDLE = (CAR)ESS <--> (ASS)ESS
NEEDLES = TRO(CAR)S <--> TRO(AT)S
SHILOVSKY = GYRO(CAR) <--> GYRO(SE)
SPUR = CAL(CAR) <--> CAL(ORY)
THREE-WHEELERS = TRI(CAR)S <--> TRI(LL)S
VEGETABLE = (CAR)ROT <--> (POI)ROT
The answers in the first half are all six letters long, and can interlock three across, three down in a grid. To disambiguate which ones are across and which ones are down, use the picture where the final column has a checkmark and the final row has an X.

Overlaying this with the 6x6 grid of letters, note that the uncovered spaces spell RUSHxHOUR, implying the next step.
Mark the requisite two- or three-letter sequences that were replaced with cars, and note the break in the border on the right side of the third row; the objective is to get the car LL (from TRILLS) out.

A shortest solution is: POI down 3, AT left 3, LL left 3, ORY up 3, POI up 3, SE left 4, ASS down 3, POI down 3, ORY down 3, LL right out. (Some moves may have order swapped with a neighbour.)
Ultimately, the two-letter across entries end covering AM and PE, and the three-letter down entries end covering REB, ALA, NCE.

Together, the answer is AMPERE BALANCE

22

This meta uses the flow chart image.

Each answer suggests a compound word or phrase composed of two animals.
AARDVARKs are also called antbears.
BRAVEST WARRIORS has a character named Catbug.
GRUMMAN made many aircraft Cats, including the Tigercat and the Bearcat. We'll want the latter for this meta.
HALF LIFE, the game, has a species called Antlions.
PET PEEVE is synonymous with bug bear.
SOCKPUPPET, in the online sense of a deceptive identity, is synonymous with catfish.
Each node on the flow chart matches with a single animal, with solid lines going from answers-first-halves to answers-second-halves, and with dotted lines going from ANT to BUG and from LION to CAT, indicating categorical connections.

The second numbers in each pair go from 1 to 7 as an ordering. The first numbers index into the animal to spell USHABTI.

25

Each answer in this meta suggests a compound word or two-word phrase where one half suggests an indexing position/a letter to select, like a cryptic crossword indicator.
Use that to select the required letter from the other half. e.g. the middle letter of MAN is A.
MEDIATOR = MIDDLE man = A
INSULT = off END = F
WIFEBEATER = tank TOP = T
CRUX = BOTTOM line = E
GINGER = red HEAD = R
EVENING TELEVISION = PRIME time = T
EYEWITNESS = FIRST hand = H
PAROUSIA = SECOND coming = O
POWER ON = START up = U
TORTURE = THIRD degree = G
DESPERATE = LAST ditch = H
INCISORS = FRONT teeth = T
Selected letters spell AFTERTHOUGHT. (Thanks to hagfy for helping to fill in the blanks.)

Gödel

This metameta relates to Incompleteness and kangaroo words. Kangaroo words are words that contain their own synonym, by taking some subset of the letters in order; e.g. BARREN has the synonym BA_RE_.
Each answer for this meta can be written in one row of the grid, such that the highlighted letters mark some but not all of the letters for the internal synonym; e.g. BARREN in the first row has the RE highlighted, but not the BA. Hence, incompleteness.

In the above picture, some answers are filled in; the pink letters are the rest of the letters for the internal synonym. These letters, in order, spell out BATTLE OF THE URUS.
Based on this, we believe that some metas that have not been solved will have the answers PARTIALLY, PERSONALITIES, and REOCCUR.

Escher

Much of the credit for this one goes to dylanamite for spotting the H-O-H pattern, and phenomist for for knowing all the angles.
This metameta relates to Water, or more specifically the molecule H2O. In a water molecule, the oxygen atom has a covalent bond with each of the hydogen atoms; the angle between these two bonds is 104.45 degrees.
Each answer for this meta contains exactly 2Hs, and one O somewhere between them. Each answer can be written on the Escher image, letters equidistant along a path that bends once with an angle of 104.45 degrees, such that: the first letter of the answer aligns with a Greek letter; the first H of the answer aligns with the left dot (under the kappa); the O aligns with the corner of the bend; the second H aligns with the right dot (under the A); and the last letter of the answer aligns with some letter on the right side.
For example, here is what the answer SCHIZOPHRENIA looks like, starting at the epsilon and ending at an L on the right side.

Ordered by the Greek letters, the answers and ending point letters are:
alpha: AFTERTHOUGHT = F
beta: THERMOCHEMISTRY = U
gamma: EACH OTHER = L
delta: ? = L
epsilon: SCHIZOPHRENIA = L
zeta: WISH YOU WERE HERE = J
eta: SHIBBOLETH = A
theta: SHORTHAND = C
iota: ? = K
kappa: HYPOTHETICAL = E
lambda: ? = T
Together, these give the answer FULL L JACKET.
Based on this, we believe that some metas that have not been solved will have the answers ECHO CHAMBER, SCHOLARSHIP, and PLAYTHROUGHS/WALKTHROUGHS. (Or any words with the same length and H-O-H positions.)

Bach

Many thanks to @ASCII-only, who posted the sheet music in The Sphinx's Lair, and to Benzopyrene for cracking this meta.
This metameta relates to Music, or more specifically the solfege notes. Luckily, with no SO/SOL in sight, these are all bigrams. Each answer for this meta contains two solfege note substrings, with two letters between them. Here is the sheet music for the Bach sound clip:
The acoustic guitar repeats a certain motif three times. In that motif, twelve notes are played in six pairs; in solfege, these are RE-DO, RE-RE, DO-DO, TI-LA, RE-LA, and MI-RE. This orders the answers, and we extract the two letters between the solfege notes in each case.
RE-DO: SCREEN DOOR = EN
RE-RE: RED GREEN = DG
DO-DO: ENDOABDOMINAL = AB
TI-LA: ?? = LE
RE-LA: AMPERE BALANCE = BA
MI-RE: ? = SE
Together, these give the answer ENDGABLEBASE.
Based on this, we believe that some metas that have not been solved will have the answers MERCANTILE LAW or FERTILE LAND, and MISERE. (Or any words with TILELA and MISERE as substrings.)

Once again, credit to @phenomist for finding the all-important external information to crack the meta.
MU puzzles involve strings of Ms, Is, and Us, and four rules for manipulating them. The four answers that feed into this meta have more letters than M, I, and U, but still each fits the pattern of one of the rules.
Rule 1: Given a string ending in I, add a U to the end. This turns the answer USHABTI into its plural, USHABTIU, meaning figurines.
Rule 2: Given a string beginning with M, take everything after the M and repeat it. This turns the answer MI into MII, an avatar on Nintendo systems.
Rule 3: Given a string containing III, replace III with a single U. This turns the answer XIII into XU, a (now defunct) coin representing one-hundredth of a Vietnamese đồng.
Rule 4: Given a string containing UU, remove the UU. This turns the answer CARDUUS into CARDS, as might be found in a pack or deck.
The four words below the image clue the modified strings, confirming the correct path. Ordering either by rule number or by length, place the modified strings into the spaces in the image, extracting the appropriate letters.
In order, the extracted letters are MIXADUHTS. Now use the values in the lower-right of the image to shift the relevant letters forwards/backwards in the alphabet to get the answer, MIXED PHOR.

What do we need to recognize metapuzzles as soon as we see them?

The four metameta answers are BATTLE OF THE URUS, FULL L JACKET, ENDGABLEBASE, and MIXED PHOR.
Each of these are actually missing their METAs: BATTLE OF THE METAURUS, FULL METAL JACKET, ENDGAME TABLEBASE, and MIXED METAPHOR.
Each answer relates to one of the original 29 metas by subject:
The BATTLE OF THE METAURUS is a famous battle of history, relating to Meta 14, all about the Epic Rap Battles of History series.
FULL METAL JACKET is a film, relating to Meta 1, all about films and film stars.
An ENDGAME TABLEBASE for a game catalogues optimal moves for specific positions; while other games have endgame tablebases, this was first and foremost applied to chess, relating to Meta 7, all about chess moves.
A MIXED METAPHOR generally refers to two well-known metaphors being combined in a flawed manner, but it can also be interpreted to mean a portmanteau, a new description created by mixing words. This clearly relates to Meta 19, all about portmanteaux.
In order, the associated metas are 14, 1, 7, and 19; spelling out NAGS in A1Z26.
Or rather, because our metas are missing METAs, metapuzzles would be a lot more easily recognizable if they were all wearing NAMETAGS.

• All three correct, nice job! (And welcome to Puzzling - great to see you here :D ) – Deusovi May 4 '18 at 23:18
• Wow, that's very impressive! I think I can help fill in 25 if you're interested: VAFHYG = bss RAQ = S, naq znlor QRFCRENGR = YNFG qvgpu = U? – hagfy May 5 '18 at 2:13
• Thanks, Deusovi; my friends and I enjoying the challenge of these metas! Also, hello, hagfy; I like your answers for 25, so I've edited my answer to add your suggestions. I can't take all the credit for these; there are a few of us collaborating on them and it's been a group effort. – ManyPinkHats May 5 '18 at 2:25
• Glad you're having fun! (And you got 25 completely correct!) – Deusovi May 5 '18 at 2:25
• That's correct, nicely done! Except... you're missing a major part of it that would explain a lot of the seemingly arbitrary decisions I made. (And several of the meta solutions, of course.) – Deusovi May 7 '18 at 3:50

I'll edit this post as more progress is made:

2

Each word contains the name of a fairly bright star that also alternatively has a Bayer designation, namely:
ARCTURUS MENGSK = α Boötis
A CAPELLA = α Aurigae
URI GELLER = β Orionis
UNICURSAL = β Eridani
PROFESSIONAL GOLFERS' ASSOCIATION = β Persei
SAVIOR = ε Carinae
Finally, index into constellation by Greek letter, giving us BARREN as the answer to this metapuzzle.

3

Googling the list of words together leads us to Pokémon - specifically, these are Pokémon categories, which, to quote Bulbapedia, are "...not often regarded as an important piece of information about a Pokémon." Anyway - these categories are unique to one Pokémon each - e.g. REVOLVING -> Inkay, PARASITE -> Nihilego, etc. Take first letters of Pokémon to get INFURIATED, the answer to this metapuzzle.

6

This puzzle was backsolved after the MMM was cracked.

Each answer has a unique double letter, so we use this to sort the answers. Furthermore, each answer is closely related to a thing listed in the first two verses of We Didn't Start the Fire, which enumerated a lot of things that happened during the Cold War. Using the order these things were mentioned in, we then convert using A=1 B=2 to get the answer ECHO CHAMBER. A fuller explanation of relations can be seen in the picture above.

7

Each word clues a letter-number combination:
FINISHED = D1 ("done")
FAR EAST MOVEMENT = G6 (Fly Like a G6)
DESTINY = F8 ("fate")
STEAK SAUCE = A1 (A1 Sauce)
DATA VISUALIZATION = D3 (D3.js)
TRITIUM = H3 (Hydrogen isotope)
GAMING CONVENTION = E3 (E3 Expo)
MISSING = G1 ("gone")
CUBE = D6 (as in a tabletop RPG)
SEARCH = F3 (F3 function key)
EXPLOSIVE = C4 (C4 explosive)
LOGORAMA = H5 (producer)
Incidentally, the letters all happen to be A-H and the numbers happen to all be in 1-8. So it would make sense that we are working with a chessboard. But where can we find additional data for a chessboard? Aha - Deusovi linked to a meta that happens to be about chess. And as it turns out, if you take the squares given in this meta and locate them on the metameta grid, the meta answer is spelled: HYPOTHETICAL.

9

Googling the list of words together leads us to "The Chaos", a fun poem about English pronunciation rules (or lack thereof). Each of the words in this list appears in the poem, and additionally each is compared to another with similar spelling but different pronunciation. For example, REVERED is compared to SEVERED, WORSE is compared to HORSE, and so on. The first letters of each of these new words gives SHIBBOLETH, the thematic answer to this metapuzzle.

11

Each word contains a symbol that can be found shifting the number row on a standard US keyboard, so we sort by this: SHEBANG, CHEAT, GEOHASHING, CURRENT DOLLAR, TWENTIETH PERCENTILE, HEALTHCARE TOURISM, WITHSTAND, STARTLING, FAIRLY ODD PARENTS. Finally, we may diagonalize, taking the nth letter from the word that contains the symbol from shift+N, to get the meta-puzzle answer SHORTHAND.

12

This puzzle was backsolved after the MMM was cracked, as well as after ffao's realization.

This puzzle uses the grid of 9x10 letters. We interpret the answers as instructions as to how to operate this maze meta. NOVICE means that we should never land on a square with the letters V, I, C, or E. STARTUP means that we should start on the top side of the grid. WEST END means that we should end on the west side. There is only one path that does this. AFTER DARK suggests how to extract the answer - upon reaching a letter D, A, R, or K, record the next letter in the path. These letters add up to spell the answer to this meta, WALKTHROUGHS.

14

This puzzle was backsolved after the MMM was cracked.
Each person or people have appeared on Epic Rap Battles of History - importantly in this series, they rap against other people/groups of people. So, we may first identify their opponents, then sort by episode, and finally, read the reverse diagonal (i.e. the 7th letter from the earliest episode, the 6th letter from the 2nd earliest episode, all the way until the 1st letter from the latest episode) to get REOCCUR.

23

Each word is a single letter change away from a spice.
GAELIC E -> R GARLIC
NARROW N -> Y YARROW
CAPED D -> R CAPER
DOLL O -> I DILL
CATNAP A -> I CATNIP
RUB B -> E RUE
JIMBO O -> U JIMBU
SAME M -> G SAGE
PAISLEY I -> R PARSLEY
NICELY N -> C CICELY
BASAL A -> I BASIL
LINGER L -> G GINGER
Taking the letters changed, we get ENDOABDOMINAL as the answer to this meta-puzzle.

24

This meta uses the following picture: .
First, we note that each of the answers contains a word that represents a circular object of some sort: BORINGHAM, COINCIDED, EARTHSYNC, ORBIT, SAUCER WITH HANDLE, SHALOM, TIRED, WOOD HOOPOE, YULE BALL. Next, we note that, if we input these words in a single square, these lengths match up with the picture, so we do that. Since some of these modified lengths are the same, we must use the X's to help disambiguate which words go where:

Given the grid, plus the fact that we have circular objects, it seems tempting to try this out as a logic puzzle, specifically Masyu, whose clues are solely of filled and unfilled circles. Promisingly, our words can also subdivided into whether they are hollow or not: RING, HALO, TIRE, HOOP are hollow and COIN, EARTH, ORB, SAUCER, BALL are not.
Now we may solve the Masyu: Once we are done, we may read out the squares that aren't traversed to get IT'S BY OH AND WI, referring to the postal abbreviations of Ohio and Wisconsin, of which the unique state that borders both is Michigan, whose abbreviation is MI. This is the meta answer.

• 2, 7, 11, and 23 are all correct! Nice job. – Deusovi May 2 '18 at 15:45

8 (not finished, but very close):

The image with eight colored arrows can be used to arrange each four-letter answer into a 2x2 grid. Translating these to Braille gives some interesting results:
Six of these bear strong resemblance to letters, but TYVM and SPXU seem garbled. It's possible there may be errors with those arrows?

10

Each answer has an embedded DNA codon starting at a different position - ACCountant, sCAThing remark, enGAGement ring, and so on. Order by position and translate to amino acids to get THERMQCHEMISTRY - as close as you can get to THERMOCHEMISTRY given that there's no amino acid with an O code.

15

The twelve alliterative answers and one unexpectedly short one match up perfectly in length and initials with the titles of the books in A Series of Unfortunate Events (minus leading articles). There's a thirteen-letter string in the Bits and Pieces section that can be translated by lining up answers with titles and finding the answer letter that matches up with the given title letter. This turns DLERCZAPSLMND into ROMAN THIRTEEN, or XIII.

16

The rows of black and white dots in the Bits and Pieces section are syllable stress patterns, with black being the main stressed syllable. Exactly two answers fit each row's pattern, and those two answers always have exactly one letter that matches in the same position. These matching letters spell EACH OTHER.

17

This one is made easier with the meta-knowledge that it's meant to be associated with the "board-games" tag. Each answer is almost entirely found in a space on the U.S. Monopoly board:
waTER[M] WORKs
co[I]MMUNITY chest
v[S]ERMONt avenue
marVIN[E] GARdens
baltiC AVE[R]Nue
The extra letters spell MISERE, one of the missing Bach answers.

19

The answers are the second halves of portmanteau words: SMOG, CHILLAX, HANGRY, INFOMERCIAL, ZONKEY, OXBRIDGE, POSITRON, HELIPORT, ROCKABILLY, EMOTICON, NETIQUETTE, INTERROBANG, and AFFLUENZA. Initials spell SCHIZOPHRENIA.

20

This one is made easier with the meta-knowledge that it's meant to be associated with the "patterns" tag. If one letter in each answer is changed, the result is a string formed by starting at a letter and making the same jump in the alphabet repeatedly:
ITEp (+11)
RErERE (+13)
FILoR (+3)
SjARIZ (-9)
SWAeI (+4)
ABcDE (+1)
tEPAL (+11)
iBUNG (-7)
WlAP (-11)
ReRER (+13)
LYlYL (+13)
IOUa (+6)
LAPEt (-11)
HUhU (+13)
APeTIX (-11)
The new letters spell PROJECTILE LATHE, one of the missing Bach answers.

27

One letter in each answer can be replaced with an X to make a new word. These letters spell INHERITOR.

28

The image in the Bits and Pieces section that seems to be two arrows above and below a red line is actually subtly a 6x6 grid tilted 45 degrees. The answers can fit going diagonally upwards and diagonally downwards, though they always clash at the crossings on the red line. These crossings are F/A, B/R, I/C, A/T, I/O, and N/S, so the answer is FABRICATIONS.

29

The answers can have a letter added to the front to make a new word. The first three have alternative possibilities (PLUMP, SLUMP, GROUSE, and GAMBLE), but the last four unambiguously spell -DUUS, which can only spell anything if the first three make it CARDUUS, a genus of thistle. [Edit: This turns out to be much less ambiguous than I thought - not only are you adding a letter to the front, you're doing so without substantially changing the meaning of the word.]

• All correct (though you missed the part in 29 that would disambiguate). Also, welcome to Puzzling! – Deusovi May 2 '18 at 19:12
• Ahh, I see what you mean now. That's an impressive bit of construction, then! – Projectyl May 2 '18 at 20:16

4

Fear of...
FROGS = Ranidaphobia
HEIGHTS = Acrophobia
DIRT = Mysophobia
BULLETS = Ballistophobia
HEAVEN = Uranophobia
DARKNESS = Nyctophobia
ENCLOSURES = Claustrophobia
THIRTEEN = Triskaidekaphobia
DOCTORS = Iatrophobia
SNAKES = Ophidiophobia
URINE = Urophobia
MIRRORS = Spectrophobia
First letter of each word = RAMBUNCTIOUS

• 4 is correct! Nice job. – Deusovi May 2 '18 at 15:45

just to build off Projectyl's answer to meta 8 with the fixed information:

I get the following image with the new third arrow and word. The 6th and 7th boxes are different as well.

This appears to give the answer to the puzzle as RED GREEN.

Hope that helps.

• Correct! (And welcome to Puzzling!) – Deusovi May 5 '18 at 16:58

The fact that ties all puzzles together that Deusovi was alluding to is:

That for the metas we solved, we can notice each of them (with one exception) can be associated with one of the tags of Puzzling Stack Exchange:

1 (Movie Artists) is the meta.
2 (Stars) is the meta.
3 (Pokémon) is the meta.
4 (Phobias) is the meta.
7 (Chess Coordinates) is the meta.
8 (Form letters) is the meta.
9 (Pronunciation) is the meta.
10 (DNA) is the meta.
11 (Hidden Words) is the meta.
14 (Epic Rap Battles of History) is the meta.
15 (A Series of Unfortunate Events) is the meta.
16 is the meta.
18 (Rush Hour) is the meta.
19 (Portmanteaus) is the Tag Fusion meta.
21 (British English) is the meta.
22 (Animal Names) is the meta.
23 (Spices) is the meta.
24 (Masyu) is the meta.
25 (Play with Words) is the meta.
27 (X Marks The Spot) is the meta.
28 (Mismatched Crossings) is the meta.
29 (Add Letters to Front) is the meta.

Of course, this list of tags is not arbitrary -- some might recognize it as the list of Fortnightly Topic Challenges that happened before the challenge, which was challenge #30! To see the whole list, you can follow this link to Puzzling Meta.

This gives us some context about the remaining metas, that might be useful when solving them:

5 is the meta.
6 is the meta.
12 is the meta.
13 is the meta.
17 is the meta.
20 is the meta.
26 is the meta.

• 26 ‘serif’ clues BACKFIRES rebus style? – TheGreatEscaper May 8 '18 at 8:28

21

These phrases are different in American and British English. When converted to British English, the two halves of the phrases have the same number of letters. Mark the changes, take the respective letters from the other half of the phrase, then sort the phrases by length. (When changing a single letter to double and vice versa, all of these letters count as change. The letter group NT in anti- /counterclockwise is not considered a change.)

    mom                   m[U]m                   t[W]i                   W
ass                   a[R]s[E]                k[I]s[S]                IS
tires                 t[Y]res                 c[H]alk                 H
humor                 humo[U]r                essa[Y]s                Y
woolen                woo[LL]en               shr[OU]ds               OU
maneuer               man[O]euv[RE]           und[E]r fi[RE]          ERE
fulfillment           fulfi[L]ment            wish t[H]eory           H
optimization          optimi[S]ation          search [E]ngine         E
counterclockwise      [A]nt[I]clockwise       [R]ev[E]rsibility       RE

The answer is WISH YOU WERE HERE.

26

Now that ffao has found out that there is a tag attached to each of the individual puzzles, we know that this is a rebus. All of the words can be interpreted as visual describtion, of other words:

    ASS                 A by SS             ABYSS
BIT                 B and IT            BANDIT
FLIT                LIFT off            LIFTOFF
GRAILS              RAIL in GS          RAILINGS
SERIF               back FIRES          BACKFIRES
IMP ... ISH         IMP over ISH        IMPOVERISH

Now we have six words of 5, 6, 7, 8, 9 and 10 letters each. You can stack them to make a nice pyramid. I didn't know how to proceed, but phenomist pointed out the correlation to the bits-and-pieces image with the ragged arrow: The four boxes correspond to the botom and top corners of the pyramid like so: