Suite Autumn
From Halopedia, the Halo wiki
Suite Autumn is a suite/medley of short music pieces included in the Halo: Original Soundtrack.
Appearances
It plays during the levels Pillar of Autumn (0:49-1:27), Halo (0:00-0:48), 343 Guilty Spark (3:02-4:24), Two Betrayals (parts 1 and 4), Keyes, and The Maw (1:28-3:01) after the Master Chief leaves the bridge and his arrival via Banshee, respectively.
Overview
The tone is somber, and somewhat ominous. The tone adds to an atmosphere of uncertainty, with the Pillar of Autumn's sharp turns sometimes you never know what's around the corner.
Trivia
The title of the piece is a play on "Sweet Autumn".