Were you looking for the Halo 3 DLC map pack known as the "Mythic Map Pack", or the Mythic Skull found in Halo 2 and'Halo 3?

"In fact, Halo 3: Mythic comes with every Halo 3 multiplayer map and you can play them all right from the disc. No need to do any downloadin'. That's pretty Mythic if you ask me."

— Urk

Halo 3: Mythic is the Halo 3 multiplayer disc that comes with Halo 3: ODST. The disc includes Halo 3's multiplayer component, Forge, the Theater, and every Halo 3 multiplayer map, including three new maps: Heretic, Citadel, and Longshore, along with their respective achievements.

Trivia

• Buying Halo 3: ODST is more cost efficient than buying all of the map packs individually, as you get the game with them.
• The armor customization screen in Halo 3: Mythic is a graphically updated version of its Halo 3 counterpart.
• The background scenes in every menu is different in comparison to Halo 3's.
• Two new demos showcasing the Mythic Map Pack and Cold Storage play when idle in the main menu.
• In the Custom Games lobby, scrolling through individual gamertags will make the Elite in the background's shoulder emblem change to same as that person's emblem.
• Citadel, Heretic, and Longshore are now available through the Mythic II Map Pack on the Xbox LIVE Marketplace for 800 Microsoft points.
• Despite being a multiplayer disc, Mythic does have an accessible Campaign lobby, but it is only viewable on Xbox LIVE if one player has the campaign disc and switches to the Campaign lobby, though the user on Mythic would not be able to play.
• The copyright text screen was changed, showing all of the available languages.
  • It also removes the game rating.

Gallery

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  The main menu of Halo 3: Mythic.

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  Screenshot on the Halo 3: Mythic disc.