Overkill (achievement)

Overkill is an achievement in Halo 3. It is awarded when a player gets 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 in December 2021, this achievement will no longer be attainable.

Background
This achievement is loathed, as it is very difficult to earn. Currently, the only permanent playlist that this achievement can 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 recent update, 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 is to use an Energy Sword on The Pit during a Swords match. Players that are skilled with the sword may be able to gain Triple Kill, Overkill, Steppin' Razor, and possibly even Killing Frenzy all in the same match. One can also rush for the Energy Sword during a King of the Hill match.
 * The turrets on The Pit can be useful when playing on that map in a Crazy King match. Players at the hill will often be too preoccupied to avoid the turret until it is too late. Alternatively, one can 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 is a valid tactic.
 * A tricky tactic is to find a Shotgun and a Bubble Shield. One can 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 can go downstairs, grab the ball, and run halfway up one of the small ramps overlooking the central "arena". At that point, one should drop the skull and hide behind the door. From there, one can melee any players that rush for the ball.
 * Several Double EXP Weekend playlists are useful for gaining this achievement, including Mythic Brawl and Ranked Living Dead.
 * In Living Dead, the Zombies are weak in a few gametypes, and some of the maps are prone to spawnkilling.