Halo 3-heads better boot up their Xbox 360 because it was recently announced that the Mythic Map Pack has officially hit Xbox Live for all to download.

Clocking in at 328.15MB the Mythic Map Pack will net you 3 new map back including Assembly, Orbital, and the all new Forge oriented map, Sandbox for just 800 Microsoft Points.

The official description of the pack, thanks to Major Nelson, is as follows:

The long-awaited Mythic Map Pack drops into Xbox LIVE Marketplace. Investigate Orbital’s abandoned hallways – before it was evacuated, the Quito Space Tether was heralded as the “Civil Engineering Monument of the Millennium.” Witness Assembly, where Scarab hulls loom overhead, being decontaminated in preparation for the city-sized Lekgolo colonies that will breathe life into the massive metal husks. An excavation site surrounded by deadly Forerunner defenses, the mysteries of Sandbox are hidden high above, deep below, and right before your eyes. There are no refunds for this item. For more information, see www.xbox.com/live/accounts.

And if you’re wondering why some people got the chance to play this before its Xbox Live street date, it’s because these same maps were included with Halo Wars.