Moonbase Alpha
From Halopedia, the Halo wiki
NOTE: This is not the actual name for the map, just a codename used by bungie.
Moonbase Alpha is a map confirmed to be used as a codename for another Downloadable Content map by bungie. it has been stated that its pretty large, so it is best suited for games like Capture The Flag and Assault. but it has also been stated that it has some unique characteristics that make Slayer interesting and Infection Terryifying.