The icon of the Mythic Map Packs is an alternate version of the difficulty icon known as Mythic. The knives are replaced with Battle Rifles, and the Mythic Skull replaces the Elite Skull. It is to be noted that Mythic has been known as a non-existent difficulty above Legendary, though Bungie has mentioned it several times on Bungie.net.
The first part of the Mythic Map Pack is a Halo 3 DLC map pack, which includes three multiplayer maps, Assembly, Orbital, and Sandbox. It was released in the Halo Wars Limited Edition. The Limited Edition was released in Asia and Australia on February 26, in Europe and Africa on February 27, and in the Americas, on March 3, with the Limited Edition version of Halo Wars. On March 23, 2009, Microsoft confirmed April 9, 2009 as the release date for Mythic as Downloadable Content (DLC) on Xbox Live for 800 Microsoft Points. In July 2010, the price dropped to 400 Microsoft Points.
The second Mythic Map Pack, titled "Mythic II Map Pack", was included on Halo 3: Mythic, the multiplayer disc included with Halo 3: ODST, which was released on September 22, 2009. The second package includes the maps Longshore, Heretic, and Citadel. The second map pack was made available as a DLC by February 2, 2010 (it can be found on Halo 3's product page on the Xbox Live Marketplace).
- Several community members received the maps early through their contributions, and many other Halo 3 players received them through community giveaways such as Halo 3 Mythbusters and Facility B5D.
- On March 2, 2009, one day before the release of Halo Wars in the US, the three Mythic maps included in the Halo Wars Limited Edition were placed on the Xbox Live marketplace for the sum of 99,999 Microsoft Points. This amounts to approximately $1,250.