The following is a spoilerific description of how the puzzle was solved....
Posted to the 8th Age topic were three images and the familiar quote "A picture is worth a thousand words." The first picture contained 30 D'ni words but for this puzzle only some of them were important. At the end of the post I wrote "~You only need to find the five~" and in another post I added the bonus clue "~Some things may be wrong but some things may be light.~". Looking again at the picture you would see that five of the D'ni words were a lighter colour than the rest. When transliterated they were the words "kormahn, lehnah, yahvo, shorah, and gahlpo". The actual translation of the words is unimportant to this puzzle.
The second posted image was of a Journey Bookmark but the image was in the shape of an old tube style tv, covered in static, and also contained a "play button" triangle and the word "tube". This should have clued you in to the fact that you'd need to find a video somewhere, the most obvious place to look being YouTube. So what to search for? This is where the D'ni words from the first image come in to play. If you searched for those words on YouTube you would find the following videos:
kormahn - http://www.youtube.com/watch?v=X36KWvZLsZw
lehnah - http://www.youtube.com/watch?v=0mvZpW24Luc
yahvo - http://www.youtube.com/watch?v=avMwhINj3DU
shorah - http://www.youtube.com/watch?v=Wn3S3o4iE7o
gahlpo - http://www.youtube.com/watch?v=dPcHg9XeOnw
Each of these videos has an image of a Journey bookmark, a D'ni number that appears near the start, and a very strange, screechy, beepy audio track. So what to do with the videos?
The third posted image was of a television test pattern with "RX-SSTV" written near the top. SSTV (Slow-scan television) is a picture transmission method used mainly by amateur radio operators, to transmit and receive static pictures via radio. It should then be clear that the audio track on the videos was an SSTV transmission. There are many programs available to decode SSTV signals but the one I found useful was the one clued to in the third image, ie RX-SSTV, which a simple google search would have found you.
To decode the image in RX-SSTV all you needed to do was play the video while the program was running and it would detect the audio portion and start decoding. Alternatively you could play the audio through your speakers and use a microphone to pick it up. The following images would result:
The final step was to take the number of the game the image was from and order them according to the numbers found in the videos:
gahlpo - #1 - Riven (ie Myst II) = 2
kormahn - #2 - Myst IV: Revelations = 4
yahvo - #3 - Myst (ie Myst I) = 1
lehnah - #4 - Myst V: End of Ages = 5
shorah - #5 - Myst III: Exile = 3
The answer for the 8th Age puzzle is 24153
Congratulations to those who solved it. I hope you all enjoyed this puzzle.