Volume 1, released at the same time as Halo 2 on November 9, 2004, contains arranged instrumental pieces written by Martin O'Donnell and his partner Michael Salvatori, as well as "inspired-by" tracks from bands Incubus, Hoobastank and Breaking Benjamin.

The soundtracks' success was pointed to as a sign of increasing legitimacy of video game music in the entertainment industry.

Incubus guitarist Mike Einziger said that "Halo is the only video game that ever inspired us to write a whole suite [of music].

O'Donnell noted that the new setting of Africa prompted him to look at "Afro-Cuban" influences, but most of this type of music did not make it to the final product.

[4] Nile Rodgers produced both volumes of the soundtrack, in addition to writing and performing the track "Never Surrender" in collaboration with songwriter/remixer Nataraj.

[1] O'Donnell stated that this presentation of the music as a concept album was natural because the overall story and atmosphere of Halo 2 directly influenced the sound to begin with.

Mike Brennan Soundtrack.net's review claimed that the inclusion of Hoobastank and Breaking Benjamin as well as Incubus made the soundtrack "more harsh" sounding but overall lacked cohesion.

[15] On the other hand, G4 TV found the four-part Odyssey by Incubus comprised "a progressive rock/fusion jam the likes of which haven't been recorded since the 1970s.

Volume 1 sold more than 100,000 copies,[20] and peaked at the number 162 position of the Billboard 200, the first video game soundtrack to ever enter the chart.

[21] The Halo 2 Original Soundtrack's success was pointed to as a sign of increasing legitimacy of video game music in the entertainment industry, which had graduated from "simple beeps" to complex melodies with big budgets.