Halo 3

There are 49 achievements with a total of 1000 gamerpoints.

20		Landfall
	Finish the first mission of the Campaign on Normal, Heroic, or Legendary.
20		Holdout
	Finish the second mission of the Campaign on Normal, Heroic, or Legendary.
20		The Road
	Finish the third mission of the Campaign on Normal, Heroic, or Legendary.
30		Assault
	Finish the fourth mission of the Campaign on Normal, Heroic, or Legendary.
30		Cleansing
	Finish the fifth mission of the Campaign on Normal, Heroic, or Legendary.
30		Refuge
	Finish the sixth mission of the Campaign on Normal, Heroic, or Legendary.
40		Last Stand
	Finish the seventh mission of the Campaign on Normal, Heroic, or Legendary.
40		The Key
	Finish the eighth mission of the Campaign on Normal, Heroic, or Legendary.
50		Return
	Finish the final mission of the Campaign on Normal, Heroic, or Legendary.
125		Campaign Complete: Normal
	Finish the Campaign on Normal.
125		Campaign Complete: Heroic
	Finish the Campaign on Heroic (unlocks achievement for Normal, if not earned).
125		Campaign Complete: Legendary
	Finish the Campaign on Legendary (unlocks achievements for Normal and Heroic, if not earned).
10		Iron
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Black Eye
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Tough Luck
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Catch
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Fog
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Famine
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Thunderstorm
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Tilt
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Mythic
	Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.
10		Graduate
	Earn 5 EXP or finish 10 games to complete the requirements for basic training (Online).
15		UNSC Spartan
	Earn your Sergeant rating to be recognized as a true Spartan (Online).
25		Spartan Officer
	Advance to the Spartan Officer ranks (Online).
5		Two for One
	Score a Double Kill with a single spartan laser shot in a ranked free for all playlist (Online).
5		Too Close to the Sun
	Destroy an enemy banshee with the spartan laser or missile pod in a ranked playlist or in campaign.
5		Triple Kill
	Kill 3 enemies within 4 seconds of one another in a ranked free for all playlist (Online).
5		Overkill
	Kill 4 enemies within 4 seconds of one another in a ranked free for all playlist (Online).
5		Lee R Wilson Memorial
	Score 5 grenade sticks in any ranked free for all playlist (Online).
5		WeÆre in for some Chop
	Destroy an enemy vehicle with equipment in a ranked playlist or in campaign.
5		Killing Frenzy
	Kill 10 enemies without dying in any ranked free for all playlist (Online).
5		Steppin' Razor
	Score a Triple Kill with the sword in a ranked free for all playlist (Online).
5		Mongoose Mowdown
	Splatter an enemy with the mongoose in a ranked free for all playlist (Online).
5		Up Close and Personal
	Kill 5 enemies by melee or assassination in a ranked free for all playlist (Online).
5		Fear the Pink Mist
	Kill 5 enemies with the needler in a ranked free for all playlist or in campaign.
5		Headshot Honcho
	Kill 10 enemies with headshots in a ranked free for all playlist or in campaign.
5		Used Car Salesman
	Destroy a vehicle that has three enemies in it in a ranked playlist or in campaign.
40		Marathon Man
	Locate and access all Terminals in the Campaign.
5		MVP
	Earn the MVP in any ranked playlist (Online).
5		Maybe Next Time Buddy
	Board the same vehicle within 10 seconds after being boarded in any free for all playlist (Online).
10		Guerilla
	Score over 15,000 points in the Campaign meta-game on the first mission.
10		Demon
	Score over 15,000 points in the Campaign meta-game on the second mission.
10		Cavalier
	Score over 15,000 points in the Campaign meta-game on the third mission.
10		Askar
	Score over 15,000 points in the Campaign meta-game on the fourth mission.
10		Exterminator
	Score over 15,000 points in the Campaign meta-game on the fifth mission.
10		Ranger
	Score over 50,000 points in the Campaign meta-game on the sixth mission.
10		Vanguard
	Score over 50,000 points in the Campaign meta-game on the seventh mission.
10		Orpheus
	Score over 15,000 points in the Campaign meta-game on the eighth mission.
10		Reclaimer
	Score over 15,000 points in the Campaign meta-game on the final mission.