Find all the hidden skulls on the Mythic maps.

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

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

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

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

On Citadel, find the hidden skull.

On Heretic, find the hidden skull.

On Longshore, find the hidden skull.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Advance to the Spartan Officer ranks (Online).

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

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

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

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

Earn the MVP in any ranked playlist (Online).

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

On Sandbox, find the hidden skull.

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

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

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

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

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

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

Locate and access all Terminals in the Campaign.

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

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

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

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

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

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

Finish the Campaign on Normal.

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

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

On Assembly, find the hidden skull.

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

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

On Orbital, find the hidden skull.