Nightfall

Nightfall is the fourth campaign level of Halo: Reach.

Upon completing this level on Normal, Heroic, or Legendary the player will unlock the "I need a weapon" achievement and 10 Gamerscore.

Summary
The mission involves Noble Six cooperating with Jun-A266 (Noble Three) in a series of stealth based encounters at night. Noble Six and Jun both make use of Sniper Rifles during this mission.

Trivia

 * A section of this level is a nighttime version of the multiplayer map Powerhouse, with some notable differences such as a large Covenant shield dome generator.
 * This is the only known level so far that features a Gueta, one of Reach's native species.
 * The target locator can be used in this level, to what extent is unknown.
 * The sniper rifle which the player uses spawns with more ammo than normal. This could possibly be unique to this level, as it is primarily a sniper mission. If so, it would be similar to the mission Truth and Reconciliation from Halo: Combat Evolved in which the Master Chief uses a sniper with above normal ammo capacity.
 * The firefight map Waterfront is based on this level.