Sandbox

Sandbox is upcoming map that will be included in the Mythic Map Pack. It's name has lead many to think that it will be a similar map to Foundry. The level's hidden skull logo, a Monitor, supports the fact that the map will be Forge based. In certain Bungie.net forum posts, there have been repeated queries as to whether there will be a larger version of Foundry, and in some cases, Bungie staff or higher ranked members have replied and said that there was one in the works.

Sandbox along with Assembly and Orbital have been confirmed to be shipped with the Limited Edition of Halo Wars. Bungie has confirmed they are working to get these maps available on Marketplace as soon as possible after Halo Wars' release on March 3, 2009. unknown. The release date for the other three maps is unknown.

In a video shown by Bungie, one of their employees cuts it off at the end when a giant spacious room similar to a VR range is shown. This could mean that Sandbox might allow you to add in different backgrounds, floor styles and make your own map without any hindrances (Apart from the Forge budget, of course).

Skull
Sandbox features a hidden skull, Sandbox Skull. This skull, when claimed, unlocks the Sandbox Skull Achievement. The crest of the hidden skull on this level appears to be a likeness of the Monitor, furthering suspicions that this will be a Forge-heavy map.

Trivia

 * On Bungie's video designed for receiving the game of the year award on G-4's G-Phoria, the Bungie crew was seen standing in a strange new place. This zone was suspected to be Sandbox.
 * This map may be a larger outdoor version of Foundry.
 * According to Bungie, they stated that "...when Orbital and Sandbox peak behind the curtains, that day won't likely be a Friday." indictating that like the previous DLC maps which were revealed on a day that wasn't a Friday, it is possible to assume that Sandbox's first official appearance may be on a Tuesday somewhere in January 2009, because in the 12/19/08 Weekly Update, Bungie stated they will not be giving anymore weekly updates till next year, but during the period of time Orbital will be revealed.
 * Sandbox still remains to be the only unrevealed map in the Mythic Map pack bundled with Halo Wars Limited Edition. Assembly and Orbital have been revealed.
 * The Sandbox seen in the pictures vaguely resembles Sandtrap if you look at the textures on the walls and floor in the lone, apparently incomplete room.
 * It may be possible that this map's forge abilities can, judging by the second image, function in a way similar to a simplified version of the Valve Hammer Editor, used to edit and create maps for Source games, along with standard forge abilities, an example of these special abilities would be sculpting structures, environments and primitives from scratch.