The following is a spoilerific description of how the puzzle was solved....
Posted in the initial topic were the clues "You'll need to piece this one together for yourself " and "Everything will come together in the end." as well as five hidden "spoilers", each titled with a link to filerio, a file sharing website. If you followed the links you'd find a download page that required a password to access, but what could the passwords be? This is where what is hidden by the "spoilers" comes in to play. Clicking on the spoilers reveals five different word/number puzzles; a crossword, a fallen phrase, a find-a-word, word tiles, and a sudoku with D'ni numbers around the outside. Each of these puzzles, when solved would provide the passwords.
~The crossword had a number of boxes highlighted. When solved you would get a string of letters, ie an anagram. The letters were "egawrrmhiote" which when unscrambled comes out as "I am the Grower" which is of course "Yeesha".
~The solved fallen phrase resulted in the phrase "I was a lord of d'ni but I fell and d'ni fell with me". This could have been either Veovis or A'gearis, and it would have been very easy to try both for the password, but the correct answer was "Veovis".
~The find-a-word, when correctly solved, would leave you with a number of letters that weren't encircled in any of the answers. The spelt out a sentence "I stand on the whark rocks". This was in reference to an art piece that Jeremy Engleman, the artist that modeled the rocks in RIven that you find the Sunners on, made for his portfolio. If you already knew about this piece then the answer would be easy, but if not a simple google search using that phrase would find the piece entitled "Sappho on the Whark rocks". The password was therefore "Sappho"
~The word tiles, when unscrambled, gave the phrase "My book of prophecy is known as the regeltavokh". This book of prophecy is referenced in a number of places in D'ni lore and is more accurately known as "The Regeltavokh of Oorpah". The password is then "Oorpah"
~Finally, the Sudoku was a little trickier as it didn't give a direct english word or phrase once solved. In the initial grid six spaces were highlighted. When solved correctly these would be "415813". This is where the D'ni numbers around the outside came in to play. They made up a key, 26 numbers corresponding to the 26 letters of the alphabet, with which you could decode the numbers into letters (D'ni #1=a, #13=b, #11=c, etc) . When completed you would get the password "Katran".
Once you had entered these passwords in at the corresponding links you would receive a .png image file containing a number of jigsaw puzzle pieces. When put together they would form an image of the D'ni cavern (an Uru concept art piece by Stephan Martinière to be specific) that I had overlayed a string of five D'ni numbers on to.
These numbers were "35412" which was the answer to the 9th Age puzzle.
Congratulations to those who solved it. I hope you all enjoyed this puzzle.