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It might not be a very Halloween-inspired release, but the soundtrack to the upcoming Halo 5: Guardians will be releasing via Microsoft on October 30th. Currently, the album is up for pre-order on Amazon in both a 2-disk CD [2] as well a a 2-vinyl LP [3] for $24.98 each, and will also presumably be released in digital formats around the same time.
Halo 5: Guardians is composed by Kazuma Jinnouchi [4], who also worked on Halo 4 alongside Neil Davidge, and was also a composer for Metal Gear Solid 4: Guns of the Patriots.
Check out sample of the soundtrack from MathChief’s second channel.