The 528 MB download costs 800 Microsoft Points and adds three new maps to the game's multiplayer 'War Games' mode, along with eight new Achievements for a total of 250 additional points.
Along with Wreckage, Harvest and Shatter maps, the DLC also includes a new game type: Extraction. This is playable in the 5-on-5 objective-based playlist.
The second and third Halo 4 map packs - 'Majestic' and 'Castle' - will be released in February and April, MS has confirmed.
Those with the Halo 4 War Games Map Pass or Limited Edition version of the game will get access to all three at no further cost.