More:Halo 3: Easy achievements
From GameWinners
Easy "Assembly Skull" achievement
Created by AchievementGuides360.
Easy "Came... From... Behind..." achievement
Created by AchievementGuides360.
Easy "Double Double" and "Road Rage" achievements
Created by AchievementGuides360.
Easy "Look Both Ways" achievement
Created by AchievementGuides360.
Easy "Marathon Man" achievement
Access the terminals and wait until the red text comes up and it redirects to a different page. It does not matter what difficulty you play on or in what order you access the terminals.
Easy "Orbital Skull" achievement
Created by AchievementGuides360.
Easy "Sandbox Skull" achievement
Created by AchievementGuides360.
Easy "Tank Dropper" achievement
Created by AchievementGuides360.
Easy "Used Car Salesman" achievement
Go to the beginning of "The Ark" mission. Make sure you have a guest or a friend to help. Continue the mission until you reach where the crashed Pelican is found (after the first terminal). Kill the blue Brute and take the rocket launcher under the crashed Pelican. Continue to where the choppers are located. As you are moving, a Prowler will drive by. Ignore it because it will soon stop and will abandon the Prowler leading to failure of the achievement. Another Prowler will follow. Have your guest or friend shoot it twice with a Brute Shot then shoot at it with your rockets. The achievement is yours. Note: If you are by yourself, do the same thing but instead of using a Brute Shot throw a grenade in front of it. Then, shoot it with the rockets.
Easy "Too Close To The Sun" achievement
In the "The Covenant" mission, you start off at a beach. Save your Spartan laser and use another gun until you get back to the beach later when you have to get in the Hornet. Fly the Hornet to a safe area around the Banshees. Get out and use your Spartan laser. Aim it at one of the Banshees and fire. If you destroy it you will get the achievement. If not, try again. You will have five shots to destroy it.
Easy "We're In For Some Chop" achievement
Go on any Campaign mission (and perhaps Co-Op) with Warthogs or Troophogs. Get all your Marines inside of one. Note: You may need a friend to stand in front or do something else to stop them from moving. Then, kill all the other Marines. Eventually the ones in the Warthog or Troophog will turn on you. Blow up the Warthog or Troophog to earn the achievement.
Easy multiplayer achievements
To pick up the "2 for 1", "Triplekill" and "Overkill" achievements easily, wait for an objective Lone Wolves match, such as King Of The Hill and Oddball. They normally require a number of players to compete in a small space. Use this opportunity gain the desired achievement.

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