And Bungie paid attention. One particularly notable anecdote from the Marathon's Story website details the mystery of the Lost Network Packets; at the site's inception, a few inconsistencies in the given dates and times of certain events arose that made the Marathon plot a little bit confusing. Rather than retroactively writing over the troublesome dates in the sequel, Bungie sent out a little tidbit side-story email to Sinclair entitled the "Lost Network Packets" that managed to rectify the dates - the date switching was intentional on the part of one of the story's AIs, said the protagonist of the Packets, as part of a defensive attempt to confuse alien hackers. Another tidbit came at the very beginning of Halo's development, where mysterious emails originating from Bungie office computers with cryptic writing styles made their way to the site by way of someone named Cortana (who would later be known as the Halo AI character). It wasn't enough for Bungie to create Marathon; they did their damnedest to create the illusion that it was a living, breathing world.
Which brings us back to Bungie itself. For the notable part of the Marathon story is not that Bungie made a pretty good game, nor that the game inspired some people to do some fairly impressive things. Rather, it's that Bungie was willing to take the game just as seriously as the fans were. Yes, Marathon players made the Vidmaster replays, but it was Bungie who issued the Vidmaster Challenge. When Marathon players were willing to invest their energies into making modifications for the game, Bungie accommodated them by releasing their own map editors with Marathon Infinity, and eventually releasing Marathon 2's source code and the whole trilogy's data files to the public. And when Marathon players began to analyze every line of text for plot significance, Bungie encouraged them with additional storyline supplements. Perhaps Bungie had this in mind while working on Halo: Marathon's success wasn't solely based on people loving it, but on people loving Bungie, too.
Pat Miller has been doing this for way too long.