Solution: 2D. I Met A Man

The coloured sections highlight fragments of this rather odd tale, and enable us to form the hypothesis that it has been created by loosely stringing together small segments, some of which have been coloured in for reasons we hope to discern.

On further inspection, it seems as though each highlighted segment acts as a clue for some word. A few seem reasonably clear: To bet on the result of a race is to GAMBLE, a mouthful of water indicates GARGLING, a fictional World War I ace is probably BIGGLES, unmarried is SINGLE, etc. A pattern is forming: With a little interpretation, it looks like we are getting a series of words that are each six-letters long and end in -LE.

Following through on this idea, we see that there are also many such clues that are not highlighted. Solving enough of the clues reveals that we have a word ladder, where a single letter changes at each step. This realisation helps to sort out some unclear answers, and we can find the complete list to be:

 A man is agilely NIMBLE biting NIBBLE a racehorse's leg, disabling it NOBBLE and causing it to teeter WOBBLE and make turkey sounds. GOBBLE Meanwhile, the chatter GABBLE of an unruly crowd RABBLE in the ruined stadium RUBBLE merges into a low growl RUMBLE as they meander about RAMBLE and bet on the result of the race, GAMBLE which is being announced incoherently GARBLE due to the announcer's mouthful of water. GARGLE A group of geese GAGGLE are being passionately bartered HAGGLE as the geese move their tails WAGGLE and the crowd vibrate WIGGLE their scarf ties WOGGLE as they stare GOGGLE and laugh. GIGGLE The man (once a fictional World War I ace) BIGGLE shakes his leg JIGGLE to a ditty JINGLE as an unmarried SINGLE Australian fashion model's BINGLE bracelet BANGLE hangs DANGLE and is carefully manipulated WANGLE by her to clatter metallically JANGLE in a tropical forest, JUNGLE but it catastrophically fails BUNGLE and they tie it with the others BUNDLE in a circular pit of crushed ore BUDDLE in a confused fashion, FUDDLE and mix up MUDDLE and interfere MEDDLE in the centre of the pit MIDDLE using a violin FIDDLE that had been cunningly stolen, DIDDLE just to waste the hours away. PIDDLE They hawk the violin PEDDLE in a pool of water PUDDLE and embrace CUDDLE but something smells bad CURDLE so they jump over a fence HURDLE and rush down a hill HURTLE in order to perform another con, HUSTLE for which they must stop her dress from dragging at the back BUSTLE and making soft crackling sounds. RUSTLE

Explanations for some of those answers:

• The scarf tie is a woggle.
• As already mentioned, the fictional World War I ace is Biggles.
• The Australian fashion model is Lara Bingle.
• To wangle is "to obtain through manipulative or deceitful methods".
• A buddle pit is used for separating minerals from lighter rock dust in crushed ore.
• Although "confused fashion" might seem to indicate MUDDLE, it is clear that MUDDLE is intended to be the answer of the next clue ("mix up"). FUDDLE is the only matching intermediate with the right meaning.
• "Piddle away" is a colloquial phrase meaning to waste, most usually with respect to time.

Now there is the task of extracting meaning from these words. A first guess would be that we should get a word from each colour, arising via extraction of a letter from each answer. Each word in a word ladder is formed by changing one letter from the previous word, so there are two special letters associated to each (except the first and last, but neither of those are relevant here since they are not coloured): The letter that is different from the previous word, and the letter that is different from the following word. We probably want one of these, or perhaps both.

Looking at just the orange words first, if we use the letters that differ from the previous words then we get WAIIJSWJDC. That does not seem at all promising! Trying instead the letters that differ from the following words gives WRIGGSWADD. That is not entirely sensible, but not complete nonsense either. Applying this to the other colours produces the following strings (choosing rainbow ordering for the colours):