Halo Online soundtrack
From Halopedia, the Halo wiki
The Halo Online soundtrack is the collection of music composed for the cancelled Halo Online. The soundtrack was composed by Tom Salta, composer of a number of other soundtracks including those of Halo: Spartan Assault, Halo: Spartan Strike, Halo: The Fall of Reach and the remastered soundtracks for Halo: Combat Evolved Anniversary and Halo 2: Anniversary. The audio studio Finishing Move Inc, primarily led by composers Brian Trifon and Brian Lee White, is also credited with working on the game's music.
Due to the game's cancellation, the soundtrack was never officially released, and the music that exists is only viewable via files extracted from the game's testing builds.