There's a forbidden vehicle in Halo 3... but I outsmarted the game devs

The most crucial vehicle in the story of Halo 3 also happens to be the most insignificant. For some reason, the game developers decided not to include the biggest, and most incredible vehicle in the game in any meaningful sense, despite fully designing it. In fact, they tried to make it 100% off-limits to players. But that doesn't mean it is.
Game: Halo 3
Difficulty: Easy
Skulls: Cowbell, Tilt, Boom, Bandanna
Players: 2+
Discord: / discord
Music Courtesy of Karl Casey ‪@WhiteBatAudio‬ (in order of appearance):
Dark Future
Whistler
Disorder
Pulse
Reliquary
Conspirator
Reliquary