Ghost Town

Almost nothing is known except that it is asymmetrical and it is a small map. It had its lighting "changed considerably" to better fit the "death-at-sunset feel." The level has been described as a bridge between nature and failed human civilization. It is reported to have many multi level, open air cat walks with sights down to semi protected alleys where you can "rain death from above".

This may be a reference to the Gunfight at the O.K. Corral, hinting the name. Much like Bungie said perfect for medium and close range battles.

Speculation
With the fact of the catwalks, it was speculated that it was a remake of one of the Halo 2 Multiplayer maps Turf or Tombstone as both featured catwalks, second stories and several alleys. This was proved to be false as it was stated on 02/04/08's Bungie Podcast that O.K. Corral, Purple Reign, and Cottonball are original maps. Bungie's mention of nature encroaching on failed civilization may imply that the level will be thematically designed after the jungle of Sierra 117 (level), similar to how Rat's Nest (level) was based on Crow's Nest (level).