Now I don’t usually post this kind of stuff, you know about what achievements are available for upcoming games. But this is Halo 3 we are talking about, what could be more important than knowing what you will be aiming for come 25th September.
Landfall - 20 
Finish the first mission of the Campaign on Normal, Heroic, or Legendary.
Holdout - 20
Finish the second mission of the Campaign on Normal, Heroic, or Legendary.
The Road - 20
Finish the third mission of the Campaign on Normal, Heroic, or Legendary.
Assault - 30
Finish the fourth mission of the Campaign on Normal, Heroic, or Legendary.
Cleansing - 30
Finish the fifth mission of the Campaign on Normal, Heroic, or Legendary.
Refuge - 30
Finish the sixth mission of the Campaign on Normal, Heroic, or Legendary.
Last Stand - 40
Finish the seventh mission of the Campaign on Normal, Heroic, or Legendary.
The Key - 40
Finish the eighth mission of the Campaign on Normal, Heroic, or Legendary.
Return - 50
Finish the final mission of the Campaign on Normal, Heroic, or Legendary.
Campaign Complete: Normal - 125
Finish the Campaign on Normal.
Campaign Complete: Heroic - 125
Finish the Campaign on Heroic (unlocks achievement for Normal, if not earned).
Campaign Complete: Legendary - 125
Finish the Campaign on Legendary (unlocks achievements for Normal and Heroic, if not earned).
Iron - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Black Eye - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Tough Luck - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Catch - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Fog - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Famine - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Thunderstorm - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Tilt - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Mythic - 10
Finish the Campaign on Normal, Heroic, or Legendary, then find and claim this skull.
Spartan Program Recruit - 10
Win your first game in matchmaking to sign up for the Spartan Program (Online).
UNSC Spartan - 15
Earn your Sergeant rating to be recognized as a true Spartan (Online).
Spartan Officer - 25
Advance to the Spartan Officer ranks (Online).
Two for One - 5
Score a Double Kill with a single spartan laser shot in a ranked free for all playlist (Online).
Too Close to the Sun - 5
Destroy an enemy banshee with the spartan laser or missile pod in a ranked playlist or in campaign.
Triple Kill - 5
Kill 3 enemies within 4 seconds of one another in a ranked free for all playlist (Online).
Overkill - 5
Kill 4 enemies within 4 seconds of one another in a ranked free for all playlist (Online).
Lee R Wilson Memorial - 5
Score 5 grenade sticks in any ranked free for all playlist (Online).
We’re in for some Chop - 5
Destroy an enemy vehicle with equipment in a ranked playlist or in campaign.
Killing Frenzy - 5
Kill 10 enemies without dying in any ranked free for all playlist (Online).
Steppin’ Razor - 5
Score a Triple Kill with the sword in a ranked free for all playlist (Online).
Mongoose Mowdown - 5
Splatter an enemy with the mongoose in a ranked free for all playlist (Online).
Up Close and Personal - 5
Kill 5 enemies by melee or assassination in a ranked free for all playlist (Online).
Fear the Pink Mist - 5
Kill 5 enemies with the needler in a ranked free for all playlist or in campaign.
Headshot Honcho - 5
Kill 10 enemies with headshots in a ranked free for all playlist or in campaign.
Used Car Salesman - 5
Destroy a vehicle that has three enemies in it in a ranked playlist or in campaign.
Marathon Man - 40
Locate and access all Terminals in the Campaign.
MVP - 5
Earn the MVP in any ranked playlist (Online).
Maybe Next Time Buddy - 5
Board the same vehicle within 10 seconds after being boarded in any free for all playlist (Online).
Demon - 10
Score over <X> points in the Campaign meta-game on the second mission.
Guerilla - 10
Score over <X> points in the Campaign meta-game on the first mission.
Cavalier - 10
Score over <X> points in the Campaign meta-game on the third mission.
Askar - 10
Score over <X> points in the Campaign meta-game on the fourth mission.
Exterminator - 10
Score over <X> points in the Campaign meta-game on the fifth mission.
Ranger - 10
Score over <X> points in the Campaign meta-game on the sixth mission.
Vanguard - 10
Score over <X> points in the Campaign meta-game on the seventh mission.
Orpheus - 10
Score over <X> points in the Campaign meta-game on eighth mission.
Reclaimer - 10
Score over <X> points in the Campaign meta-game on the final mission.
