Today Microsoft released the first set of downloadable content for Halo 3. The download pack contains three maps, each designed to offer a different style of play.
The map Standoff, for instance, is a symmetrical valley that has
bases at the ends. This is perfect for capture the flag. Rat’s Nest is
a maze of hallways meant for up close and personal deathmatch games.
The third map, Foundry, is a warehouse, designed to allow players to
utilize the Forge editor and make their own map.
The DLC will run you 800 Microsoft Points ($10), however the map
will become free when the second map pack is released next spring.