From Halopedia, the Halo wiki
Opening Suite is the first track in Halo: Original Soundtrack. It is composed of four untitled movements: the music for the Bungie logo sequence (0:00-0:10), a variation of the Halo Theme Gregorian chant (0:11-0:36), the Halo Theme Gregorian chant (0:37-1:06), and the space theme (1:07-3:33).
The entire track except for the first section was arranged into Random Slipspace Trajectory in the Halo: Combat Evolved Anniversary Original Soundtrack.
Bungie logo theme
The track opens with a strong and upbeat percussive piece (0:10). It plays in the opening Bungie logo sequence.
Halo Theme Gregorian chant variation
A variation of the Gregorian chant from the Halo Theme (0:25) features vocals singing a chord progression derived from the Halo Theme. It plays:
- During the opening cinematic of the level The Pillar of Autumn, when John-117 is released from his cryo chamber.
- In the campaign level The Truth and Reconciliation, during the cinematic in which Jacob Keyes is rescued, when Cortana talks about Halo possessing a religious significance to the Covenant.
- During the opening cinematic of the level Keyes, when the Covenant are seen fighting the Flood underneath the Truth and Reconciliation.
A arrangement of the progression was incorporated into the introduction of the music played during the Warthog run in the Halo 3 campaign level Halo, though it was omitted from Greatest Journey, the corresponding track from the soundtrack. The piece, along with the following section, was also arranged into Opening Suite 1 in Halo: Legends Original Soundtrack. The Halo: Combat Evolved Anniversary rendition of the chant was incorporated into the tracks Heliopause and Didactic Principal.
Halo Theme Gregorian chant
The Gregorian chant from the Halo Theme (0:29) features the four phrases of Halo Theme Gregorian chant. It plays in the main menu of Halo: Combat Evolved.
This section, along with the previous section, was arranged into Opening Suite 1 in Halo: Legends Original Soundtrack.
The space theme (2:26) features low and high strings playing a suspenseful melody. The high strings introduction was first featured in the opening of the Halo E3 2000 trailer. The piece plays in the opening cinematic of the campaign level The Pillar of Autumn. It then plays again during the campaign level Two Betrayals, while John-117 is flying a Type-26 Banshee to the second phase pulse generator.
The piece was arranged into Cold Blue Light (from the track Cairo Suite), with a short reprise in Penance (from the track Delta Halo Suite), in Halo 2: Original Soundtrack. Cold Blue Light also plays in the Epilogue/credits of Halo: Reach in place of Opening Suite when recreating the opening scene of Halo: Combat Evolved. Cold Blue Light was then arranged into Only a Star, Only the Sea in Halo 2: Anniversary Original Soundtrack.
The space theme's melody was also featured in the tracks Opening Suite 2, Cairo Suite 1 and Delta Halo in Halo: Legends Original Soundtrack. For Halo: Combat Evolved Anniversary, a full arrangement of the theme was featured in the track Random Slipspace Trajectory, and then incorporated into the ending of the track Unreliable Exploration. The string melody, along with elements of the Halo 3 track Luck was incorporated into the opening section of Osiris Suite, Act 1 in Halo 5: Guardians Original Soundtrack.