Great review, agree with most everything in it to the point I don't think I can add too much. Really liked how faithful O'Donnell and Salvatori are to many of the themes established here in later scores, especially 2 and 3, especially "Under Cover Of Night" which becomes arguably one of the main themes of Halo 3. This is a "greater than the sum of it's parts" sort of score for me. So I guess I'll add a bunch of interesting tidbits: if you're a fan of this score, make sure you have the missing track "The Lost Song" or "The Lost Muse" added onto your release: it was accidentally left off the original album for some reason, which is a shame because it continues some of that beautiful ambient alien wonder that extends from "A Walk In The Woods" and "Under Cover Of Night" that many people find enticing about this score, myself included, and which unfortunately gets dialed out as the series progresses to more militaristic fanfare and more straight-laced fantasy fare.

https://www.youtube.com/watch?v=awjiVkHOKtM&ab_channel=AUELRTEX

O'Donnell also released a bunch of demos and sketches for this first game which are... interesting for a listen or two, especially in how much the sound and tone shifted, but personally not much more than that. I'm really glad O'Donnell and Salvotori moved away from this direction, these demos felt a lot closer to game music you'd expect from the 90s/early 2000s (like Bungie's previous Marathon titles). Here's an example below.

https://www.youtube.com/watch?v=a3bhHDGk4qA&ab_channel=AwesomeHaloMusic%5BUncookedMoa%5D

Looking forward to your takes on 2 and 3, even if I have a feeling what you're gonna say.