Sandbox

Sandbox is upcoming map that will be included in the Mythic Map Pack. Its setting and architechture is similar to Sandtrap, but its forge capabilities seem to be on par with Foundry. The level's hidden skull logo, a Monitor, supports the theory 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 February 26, 27, and March 3 2009. The release date for the other three maps is unknown although it is speculated that they will come with Halo 3:ODST.

"Forerunner structures are often so vast, so towering and so exaggerated that they'd be visible from a number of different excavation sites."

- Lukems posted a brief clue about Sandbox's location in the Halo universe on 01.20.2009 2:40 PM PST

This may refer to Sandtrap as it was a desert-based excavation site. This theory has since been confirmed by the series of screenshots that have been released by Bungie.

Setting
Sandbox is set in the midst of a barren desert with many rolling sand dunes, similar to Sandtrap. Large Forerunner towers can be seen in the distance. It seems that the map may actually be set on a moon (similar to Halo 2's Burial Mounds), as a crescent shape can be seen in the sky of one of the screenshots. The crescent seems too large to be a moon itself, implying that it is the planet, and the player is on the moon. Bungie hinted that, similar to Sandtrap, the Covenant may have also conducted archaeological excavations here.

Default Sandbox
The default sandbox is perfectly symmetrical, and considered by Bungie to be a medium-large map. It contains two bases opposite each other, with cover laid in between. The map's vehicular arsenal includes a Chopper, Warthog and two Mongooses for each team. The infantry has Rocket Launchers and Missile Pods to counter them, and an overshield is located on top of a pillar in the center of the map.

Sky Bubble
The Sky Bubble is essentially an area in Sandbox that can be reached via a teleporter, so you can play on both the normal map and the Sky Bubble at the same time.. It is located high above Sandbox's ground level, and has another grid system to help line up objects. The sky bubble is completely flat, and based on screenshots, appears to be larger than the ground area of the default Sandbox. When you fall off the edge of your forge from the sky bubble, there is a death barrier, so maps like guardian can be made.

Forge
""Sandbox combines large-scale vehicular combat with a limitless amount of Forge customization. Boasting a tiered, open-world layout, “Halo 3” players will be able to build their own unique game experiences using the Forge map editor. Sandbox is a map unlike any Bungie has ever created.""

- Bungie.net

The center of the map is a flat, empty floor, similar to Foundry but visually resembling Sandtrap. The map is built from forge-editable blocks, pillars and ramps. The map is said to include "just about every kind of building block you could ever want", for example tunnels, crouch-only doorways and quarter-pyramids. Sandbox will likely have more vehicles available than Foundry; the confirmed vehicles are Warthogs, Scorpions, Mongooses, Choppers, and Scorpions; and no vehicles were present in the default Foundry. A new Forge item is an orb of light that colors its surroundings in either red or blue; it can be used to differentiate the two bases, similar to most maps made by Bungie. Another is the "Kill Ball" that kills anyone who enters it. Also, in Forge mode, a blue-grid appears on the map to help the player place objects straight.

Skull
Sandbox features a hidden skull, the Sandbox Skull. This skull, if obtained, unlocks the Sandbox Skull Achievement. The crest of the hidden skull on this level appears to be a likeness of the Monitor.

Trivia

 * In the new screenshot released by Bungie, Sandbox seems to be a small-medium sized map, possibly about the size of Standoff, with obvious resemblance to Sandtrap. Sandbox may be the desert-theme map of Foundry as the structures within the screenshot are speculated to be scenery objects players can move.
 * The vehicles on map, which are the Mongoose, Warthog and Chopper, are the same as Sandtrap, with the only difference having 2 Warthogs less, possibly the respawn times for the vehicles are longer and the land surfaces are more even. There is also two Scorpion tanks that were spotted in the T3.com interview.
 * Upon careful examination of the first screenshot, the boundaries of the map are protected by another Brute mine field as seen before in Sandtrap. You can see the short light warning posts on the left side of the map.
 * After Blackout, it is the second map to be set in the dark, though the lights emanating from the pillars in the distance negate it. It is also the third map with a setting sun, behind Standoff and Ghost Town.
 * On the IGN interview with Dan Miller he stated that with the Skybox, Sandbox is the biggest map in the game.