Finish the first mission of the Campaign on Normal, Heroic, or Legendary.

Unlocked: Offline

Finish the second mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the third mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the fourth mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the fifth mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the sixth mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the seventh mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the eighth mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the final mission of the Campaign on Normal, Heroic, or Legendary.

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Finish the Campaign on Normal.

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Finish the Campaign on Heroic (unlocks achievement for Normal, if not earned).

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Finish the Campaign on Legendary (unlocks achievements for Normal and Heroic, if not earned).

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Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

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Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Find and claim this skull when playing on Normal, Heroic or Legendary difficulty.

Unlocked: Offline

Earn 5 EXP or finish 10 games to complete the requirements for basic training (Online).

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Earn your Sergeant rating to be recognized as a true Spartan (Online).

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Advance to the Spartan Officer ranks (Online).

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Score a Double Kill with a single spartan laser shot in a ranked free for all playlist (Online).

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Destroy an enemy banshee with the spartan laser or missile pod in a ranked playlist or in campaign.

Unlocked: Offline

Kill 3 enemies within 4 seconds of one another in a ranked free for all playlist (Online).

Unlocked: Offline

Kill 4 enemies within 4 seconds of one another in a ranked free for all playlist (Online).

Unlocked: Offline

Score 5 grenade sticks in any ranked free for all playlist (Online).

Unlocked: Offline

Destroy an enemy vehicle with equipment in a ranked playlist or in campaign.

Unlocked: Offline

Kill 10 enemies without dying in any ranked free for all playlist (Online).

Unlocked: Offline

Score a Triple Kill with the sword in a ranked free for all playlist (Online).

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Splatter an enemy with the mongoose in a ranked free for all playlist (Online).

Unlocked: Offline

Kill 5 enemies by melee or assassination in a ranked free for all playlist (Online).

Unlocked: Offline

Kill 5 enemies with the needler in a ranked free for all playlist or in campaign.

Unlocked: Offline

Kill 10 enemies with headshots in a ranked free for all playlist or in campaign.

Unlocked: Offline

Destroy a vehicle that has three enemies in it in a ranked playlist or in campaign.

Unlocked: Offline

Locate and access all Terminals in the Campaign.

Unlocked: Offline

Earn the MVP in any ranked playlist (Online).

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Board the same vehicle within 10 seconds after being boarded in any free for all playlist (Online).

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the first mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the second mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the third mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the fourth mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the fifth mission.

Unlocked: Offline

Score over 50,000 points in the Campaign meta-game on the sixth mission.

Unlocked: Offline

Score over 50,000 points in the Campaign meta-game on the seventh mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the eighth mission.

Unlocked: Offline

Score over 15,000 points in the Campaign meta-game on the final mission.

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On a Legendary map, get two Double Kills during any ranked or social match.

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On a Legendary map, get 3 Oddball melee kills during any ranked or social match.

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On a Legendary map, get 3 assassinations during any ranked or social match.

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On a Legendary map, get a flag melee kill during any ranked or social match.

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On a Legendary map, get 2 flag carrier kills during any ranked or social match.

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On a Legendary map, get 5 Warthog chaingun kills during any ranked or social match.

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On a Legendary map, get a Splatter Spree during any ranked or social match.

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On Assembly, get 5 Hammer kills during any ranked or social match.

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On Orbital, get 2 Death From the Grave medals during any ranked or social match.

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On a Mythic map, get a Bulltrue medal during any ranked or social match.

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On a Mythic map, get a Killjoy medal during any ranked or social match.

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On a Mythic map, get a Killtacular during any ranked or social match.

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On a Mythic map, get an Extermination during any ranked or social match.

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On a Mythic map, get a Perfection medal during any ranked or social match.

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On a Mythic map, infect 2 humans during any ranked or social match.

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On a Mythic map, kill 2 Zombies during any ranked or social match.

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On any Mythic map, get a kill on another player while in monitor mode.

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On Assembly, find the hidden skull.

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On Orbital, find the hidden skull.

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On Sandbox, find the hidden skull.

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On Citadel, get a Shotgun Spree during any ranked or social match.

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On Heretic, get a Sword Spree during any ranked or social match.

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On Longshore, get 3 kills with a Ghost during any ranked or social match.

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On Citadel, find the hidden skull.

Unlocked: Offline

On Heretic, find the hidden skull.

Unlocked: Offline

On Longshore, find the hidden skull.

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After 9/25/08, complete Halo on 4-player Legendary LIVE co-op, with Iron, and everyone in Ghosts.

Unlocked: Offline

Find all the hidden skulls on the Mythic maps.

Unlocked: Offline

Get to the rank of Lieutenant in any playlist in the new EXP progression system.

Unlocked: Offline

Enter into any ranked or social playlist with 7 EXP on the 7th of the month.

Unlocked: Offline