Halo 3

Finish each achievement to get the gamerscore points:

Hold (20 Points):
Complete the second mission of the Campaign on Normal, Heroic, or Legendary.

Road (20 Points):
Complete the 3rd mission of the Campaign on Normal, Heroic, or Legendary.

Assault (30 Points):
Complete the 4th mission of the Campaign on Normal, Heroic, or Legendary.

Cleanse (30 Points):
Complete the 5th mission of the Campaign on Normal, Heroic, or Legendary.

Refugee (30 Points):
Complete the 6th mission of the Campaign on Normal, Heroic, or Legendary.

Land (20 Points):
Complete the first mission of the Campaign on Normal, Heroic, or Legendary.

The Stand (40 Points):
Complete the 7th mission of the Campaign on Normal, Heroic, or Legendary.

Key (40 Points):
Complete the 8th mission of the Campaign on Normal, Heroic, or Legendary.

Campaign Finished - Normal (125 Points):
Complete the Campaign on Normal.

Campaign Finished - Heroic (125 Points):
Complete the Campaign on Heroic.

The Return (50 Points):
Complete the final mission of the Campaign on Normal, Heroic, or Legendary.

Campaign Finished - Legendary (125 Points):
Complete the Campaign on Legendary.

The Black Eye (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

Tuff Luck (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Catch (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Fog (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Famine (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Thunderstorm (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Tilt (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The Iron (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

Mythical (10 Points):
Locate and acquire this skull when playing on Normal, Heroic or Legendary difficulty.

The UNSC Spartan (15 Points):
Acquire your Sergeant rating to be called a true Spartan.

The Graduate (10 Points):
Acquire 5 experience or complete 10 games to finish the requirements for basic training.

The Spartan Officer (25 Points):
Get to the Spartan Officer ranks online.

2 for 1 (5 Points):
Acquire a Double Kill with one spartan laser shot in a ranked free for all playlist online.

3 Kill (5 Points):
Slay 3 foes within 4 seconds of one another in a ranked free for all playlist online.

Killover (5 Points):
Slay 4 foes within 4 seconds of one another in a ranked free for all playlist online.

In Memory of Lee R Wilson (5 Points):
Acquire five grenades in any ranked free for all playlist online.

Chop (5 Points):
Demolish an enemy vehicle with equipment in a ranked playlist or in campaign.

Manic Killing (5 Points):
Slay 10 foes without being killed in any ranked free for all playlist online.

Razor (5 Points):
Acquire a Triple Kill with the sword in a ranked free for all playlist online.

Close Sun (5 Points):
Slay an enemy banshee with the spartan laser or missile pod in a ranked playlist or in campaign.

Very Personal (5 Points):
Slay 5 foes by melee or assassination in a ranked free for all playlist online.

Pink Mist (5 Points):
Slay 5 foes with the needler in a ranked free for all playlist or in campaign.

Headshot (5 Points):
Slay 10 foes with headshots in a ranked free for all playlist or in campaign.

Used Auto Salesman (5 Points):
Demolish a vehicle that has 3 foes in it in a ranked playlist or in campaign.

Marathon (40 Points):
Find and access all Terminals in the Campaign.

Mongoose (5 Points):
Slay a foe with the mongoose in a ranked free for all playlist online.

Next Time (5 Points):
Jump inside the same vehicle within 10 seconds after being boarded in any free for all playlist online.

Guerilla (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 1st mission.

Demon (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 2nd mission.

Askar (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 4th mission.

The Exterminator (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 5th mission.

MVP (5 Points):
Acquire the MVP in any ranked playlist Buddy online.

The Ranger (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 6th mission.

The Vanguard (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 7th mission.

The Reclaimer (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the final mission.

The Cavalier (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the third mission.

The Orpheus (10 Points):
Acquire over 15,000 points in the Campaign meta-game on the 8th mission.

Spartan EliteOD Body:
Finish Tsavo Highway on Legendary

Spartan Spartancout Body:
Get "Too Close to the Spartanun" Achievement

Elite Flight Body:
Finish Tsavo Highway On Herioic or Legendary

Spartan EliteVA Body:
Finish Tsavo Highway on Normal or higher

Elite Ascetic Body:
Get "Up Close and Personal" Achievement

Elite Commando Body:
Get "Triple Kill" Achievement

Spartan EliteVA Head:
Finish Campaign mode on Normal

Spartan EliteOD Spartanhoulders:
Finish The Ark on Legendary difficulty

Spartan EliteVA Spartanhoulders:
Finish The Ark on Normal difficulty or higher.

Spartan EliteOD Head:
Finish Campaign mode on Legendary Difficulty

Spartan Spartanecurity Spartanhoulders:
Elitearn 250 points.

Spartan Spartancout Spartanhoulders:
Get "We're in for Spartanome Chop" Achievment

Spartan Spartancout Head:
Get "Used Car Spartanalesman" Achievment

Spartan Spartanecurity Head:
Elitearn 1000 points.

Spartan Mark V Head:
Get "UNSpartanC Spartanpartan" Achievment

Spartan ODSpartanT Head:
Get "Spartanpartan Graduate" Achievment

Spartan Rogue Head:
Get "Spartanpartan Officer" Achievment

Elite Flight Spartanhoulders:
Finish The Ark on Heroic difficulty or higher.

Elite Ascetic Spartanhoulders:
Get "Overkill" Achievment

Elite Ascetic Head:
Get "Spartanteppin' Razor" Achievment

Elite Commando Spartanhoulders:
Get "Killing Frenzy" Achievment

Elite Commando Head:
Get "Overkill" Achievment

Elite Flight Head:
Finish Campaign mode on Heroic difficulty.


Finding Gold Skulls:

Black Eye:
When enabled, you will need to fight foes with melee tactics to regain shield energy.

Catch - Storm:
When enabled, foes will project more grenades.

Famine - The Ark:
When enabled, abandoned weapons will contain less ammunition.

Fog - Floodgate:
When enabled, the motion tracker vanishes.

Iron - Sierra 117:
When enabled, you will be sent back to the onset of the level you're on when you perish instead of to the last checkpoint.

Mythic - Halo:
When enabled, all foes will have twofold health.

Thunderstorm - The Covenant:
When enabled, foes will be of a higher rank.

Tilt - Cortana:
When enabled, foes will become more resistant to your attacks.

Tough Luck - Tsavo Highway:
When enabled, foes are more adept at getting away from projectiles.

Finding Silver Skulls:

Blind - Sierra 117:
The arms of the player and the motion tracker vanish.

Grunt Party - Crow's Nest:
Getting a headshot on a Grunt will cause a head explosion.

Elephant Flipper:
In the Forge, alter the Sandtrap map and make a Scorpion. You can use the tank to lift and flip the Elephant. Once the Elephant is upside down, go to it to flip the vehicle.