Overkill (achievement)

Overkill is an achievement in Halo 3. It was awarded when a player earned an Overkill medal in a ranked free-for-all Matchmaking playlist. The achievement is worth, and unlocks the Elite Commando helmet and the Elite Ascetic shoulder armor permutations.

Following the shutdown of Xbox 360 Halo online services on January 13, 2022, this achievement is no longer attainable.

Background
This achievement is known for being very difficult to earn. The only permanent playlist that this achievement could be earned in is Lone Wolves. Lone Wolves originally only supported five-player matches, such that an Overkill Medal required the killing of every other player in the match. This proved to be quite difficult, and many players instead opted to get this achievement simply in an achievement match.

This was rectified and made slightly easier in a later updates, where the amount of people allowed per match was increased to six.

Rewards
Unlocking this achievement rewards the player with the following;
 * Commando helmet multiplayer armor permutation
 * Ascetic shoulders multiplayer armor permutation
 * Ascetic shoulders multiplayer armor permutation

Tactics

 * One way to get this achievement was to use an Energy Sword on The Pit during a Swords match. Players that are skilled with the sword were be able to gain Triple Kill, Overkill, Steppin' Razor, and possibly even Killing Frenzy all in the same match. One could also rush for the Energy Sword during a King of the Hill match.
 * The turrets on The Pit could be useful when playing on that map in a Crazy King match. Players at the hill would often be too preoccupied to avoid the turret until it was too late. Alternatively, one could lie in wait near the hill with a Shotgun, gravity hammer, or Mauler.
 * During a King of the Hill match, sniping players at the hill was a valid tactic.
 * A tricky tactic was to find a Shotgun and a Bubble Shield. One could activate the Bubble Shield to draw enemies close, and then use the Shotgun to mow them down when they enter.
 * During an Oddball match on Guardian, one could go downstairs, grab the ball, and run halfway up one of the small ramps overlooking the central "arena". At that point, one could drop the skull and hide behind the door. From there, one could melee any players that rush for the ball.
 * Several Double EXP Weekend playlists were useful for gaining this achievement, including Mythic Brawl and Ranked Living Dead.
 * In Living Dead, the Zombies were weak in a few gametypes, and some of the maps were prone to spawnkilling.