Man, this whole mess with Bungie and Marty O'Donnell is wild. Basically the gist is:

• Several months ago, Marty chose to offer free downloads for some of the music he created for various game soundtracks over the years (including Myth and Oni). He also had some of his music posted on his own Youtube channel, de-monetized.
• Yesterday, he tweets about how he is considering retiring from the games industry, then tweets that he might have to delete his personal Youtube channel, and when someone asks why, he says "ask Pete Parsons" (the CEO of Bungie). All of those tweets are deleted now today.
• Today he tweets about his new album, asking people to buy it, saying that he needs the money to pay for his huge legal bills. All of the pieces of evidence seem to line up with Bungie suing Marty over offering free downloads of some of his older songs, and re-posting his songs on his personal, de-monetized youtube channel.
• All of this of course coming after Bungie fired Marty in 2014, denying him pay for unused vacation and sabbatical time, closing his stock out, and denying him participation in Bungie's employee profit sharing plan for his work on Destiny's soundtrack. He sued Bungies' CEO at the time, Harold Ryan, for wrongful termination and won that suit, and also won his suit against Bungie for his stock being closed and his removal from the employee profit sharing plan.

In short, modern Bungie is super corporate and shitty. 

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But he was right, Destiny Reddit wouldn’t even exist without him, because Halo would have never got popular enough for Destiny to be created without Marty’s Halo soundtrack. ...

It was for me. The very first thing I noticed about Halo was the soundtrack. The Halo 1 and 2 soundtracks were two of the first game soundtracks to actually sell well on their own when released, there is a reason why Marty is credited with legitimizing the video game music industry; before Halo came around,  game soundtrack composition had a negative connotation, just like being a game developer did before the 2000’s.

I personally don’t think Halo would have even sold half the copies that it sold with a different soundtrack. The Halo theme is absolutely iconic, it completely made the Halo pre-release trailers at Mac World and E3 for me, without that theme those pre-release trailers were kind of bland honestly. There have been many critics who have noted that Marty’s theme on those early trailers helped to build hype for the game, seeing as sci-fi games were relatively niche before Halo came around.

And while it’s true that Michael Salvatori assisted on all of the Halo soundtracks, Michael came on late for Halo 1, he stayed behind to run their co-owned music company for awhile while Marty did the initial work on Halo’s soundtrack alone at Bungie. Not trying to diminish Michael’s work on the series, he made significant contributions on all of the soundtracks, but less so on the first Halo than on the later ones. The idea for the iconic Halo main theme was all Marty, though Michael helped record the actual Gregorian chant on it.

Something else that's noteworthy about Halo's soundtrack is how dynamic it was. At that time, the vast majority of games had set soundtracks that looped over and over until a level was finished, but Marty designed Halo's soundtrack to be dynamic, so that it could change and evolve over the course of the level. He worked closely with the level design team to design the soundtrack in chunks that could re-combined or looped as needed based on where the player was at in the individual level and what they were doing in the game at the time, and to prevent fatigue from hearing the same thing over and over again. At the time this was a pretty revolutionary concept for game audio. His dynamic soundtrack idea caught on and is now used in many games today.

O'Donnell designed the music so that it "could be dissembled and remixed in such a way that would give [him] multiple, interchangeable loops that could be randomly recombined in order to keep the piece interesting as well as a variable-length". Development involved the creation of "alternative middle sections that could be transitioned to if the game called for such a change (i.e. less or more intense)." O'Donnell sat with the level designers to walk through the levels, constructing music that would adapt to the gameplay rather than be static; "The level designer would tell me what he hoped a player would feel at certain points or after accomplishing certain tasks." Based on this information, O'Donnell would develop cues the designer could script into the level, and then he and the designer would play through the mission to see if the audio worked. He made sparse use of music because he believes that "[music] is best used in a game to quicken the emotional state of the player and it works best when used least," and that "[if] music is constantly playing it tends to become sonic wallpaper and loses its impact when it is needed to truly enhance some dramatic component of gameplay."