Sierra 117

Landfall is believed to be the first campaign mission of Halo 3.

It takes place in a jungle.

It was likely named because SPARTAN-117 disembarks from the Forerunner Ship onto the lands of Earth, although this is unconfirmed.

This is unlikely, however, because the comic series Halo: Uprising takes place after the ending of Halo 2. Or it is possible that the Chief will be inserted via Orbital Drop, or Pelican insertion as well.

Upon completing it on the Normal, Heroic, or Legendary difficulties, the player will earn the "Landfall" achievement and 20 Gamerpoints.