Skulls...
	Various Steam Achievements...

Grunt Birthday Party
In the "A New Enemy" mission, capture all four of Decimus' power nodes in the second part of the map. Once you capture the third power node, it will display icons on the map with the locations of the remaining power nodes. The skull's effect is killed grunts explode into confetti.

Paintball
In The "Ascension" mission, completely destroy the Banished base in the northern area of the map. The skull's effect is marine grenades and grunt mines explode with color.

Pain Train
In the "Ascension" mission, fly to the island in the southeast corner of the map and destroy the four hidden Aug. Extrators. Note: It cannot be accessed normally; send Hornets to destroy it. The skull's effect is all player units train 50 percent faster. The final score will also decrease.

Bountiful Harvest
In the "One Three Zero" mission, do not allow any of the captured prisoners (four prison squads) to die. It is recommended to play on the Easy difficulty to make completing this challenge much less difficult. Try keeping the prisoners in the back lines to better protect them. The skull's effect is supplies from supply pads arrives 25 percent faster. The final score will also decrease.

Emperor
In "The Cartographer" mission, before going to the top conduit, destroy both Banished minibases on the west and east sides in the central chamber. The skull's effect is all player powers recharge in half the time. The final score will also decrease.

Pestilence
In the "Lights Out" mission, rescue all ten squads of UNSC prisoners. The first prisoner is found to the right at the beginning of the mission. The other prisoners can be found slightly to the right of the center of the map. The skull's effect is all player units slowly lose health from the moment they are built. The final score will also increase.

Total Annihilation
In the "From The Deep" mission, successfully complete the mission without any Spartan soldiers being killed. Simply retreat when their shields are low to prevent them from dying. The skull's effect is the Spartan "Slams" special ability creates a more powerful explosion upon landing. The final score will also decrease.

Sickness
In the "Hold The Line" mission, successfully complete the mission without losing a single barricade. It is recommended to play on the Easy difficulty to make completing this challenge less difficult. The skull's effect is all player units have 50 percent fewer hit points. The final score will also increase.

Firestarter
In the "Hold The Line" mission, have the Particle Cannon stay above 50 percent health. It is recommended to play on the Easy difficulty to make completing this challenge much easier. The skull's effect is grunts and marines explode upon death, inflicting damage on enemy units. The final score will also decrease.

Things That Make You Go Boom
In the "Under The Dark" mission, defeat all three Brute Warlords. The skull's effect is hero units release a nuclear explosion upon death. The final score will also decrease.

Wuv Woo
In "The Foundry" mission, have the Scarab survive the mission. It is recommended to play on the Easy difficulty to make completing this challenge much easier. The skull's effect is Scarab and Locust beam weapons shoot rainbows.

Sugar Cookies
In "The Foundry" mission, have the Scarab stay above 25 percent health. It is recommended to play on the Easy difficulty to make completing this challenge much easier. The skull's effect is all player units have 50 percent more hit points. The final score will also decrease.

After Party
In "The Halo" mission, defend Bravo base in the northeast corner of the map. Kill all the enemies and eventually it will become operational. The skull's effect is any time a Firebase is destroyed, the player who owned it gets a tank and infantry unit. The final score will also decrease.

Nightmare
In the "Last Stand" mission, do not allow the Control Room shield to take more than 25 percent damage. It is recommended to play on the Easy difficulty to make completing this challenge much easier. The skull's effect is no checkpoints or saves allowed on any difficulty in the campaign only. The final score will also increase.

Shadow
In the "Last Stand" mission, defeat both Brute Warlords -- one is on the southeast edge of the map, and the other is on the southwest edge. The skull's effect is all infantry units start cloaked. The final score will also decrease.

Complete the indicated task to unlock the achievement.

Achievement	How to unlock
A history of decimation (10 points)	Complete A New Enemy.
A little bit extra (10 points)	Complete half of the Campaign bonus objectives.
A lot extra (20 points)	Complete all the Campaign bonus objectives.
A strong showing for the week (10 points)	Complete a set of 3 Weekly Challenges in one week.
Alas, poor Yorick! (10 points)	Collect a Skull.
All or nothing (10 points)	Play all cards in your deck at least once in a single Blitz match.
All travel is suspended (10 points)	Complete Lights Out.
And the knockout punch (10 points)	Complete Under the Dark.
Ante-up (10 points)	Complete the Blitz tutorial.
Behind enemy lines (10 points)	Complete From the Deep.
Big Spender (30 points)	Spend 100 Leader Points in Multiplayer or Skirmish.
Card shark (20 points)	Complete 25 Blitz matches (Matchmaking only).
Collecting a dream (30 points)	Collect all the Skulls.
Comrades in arms (20 points)	Earn a gold medal on any mission (except Prologue) in Co-op on Legendary.
Dominated (10 points)	Complete Ascension.
Duellist (10 points)	Win your first Blitz match (Matchmaking only).
Fifth floor: Tools, Guns, Super Weapons (10 points)	Complete The Foundry.
Firefighter (10 points)	Beat wave 10 in Blitz Firefight.
First steps (10 points)	Complete a Multiplayer match (Matchmaking only).
Flyswatter (20 points)	Destroy 100 air units with anti-air units (Multiplayer, Skirmish or Blitz).
Full house (10 points)	Complete Blitz matches as each of the 6 launch leaders (Matchmaking only).
Gold rush (20 points)	Earn a gold medal on any mission (except Prologue) on any difficulty.
Guerilla tactics (10 points)	Complete One Three Zero.
It just keeps going (30 points)	Beat wave 25 in Blitz Firefight.
Jackpot (40 points)	Play 777 total Blitz cards over any number of matches.
Know the ropes (10 points)	Complete the Advanced standalone tutorial.
Last stop, this town (10 points)	Complete Last Stand.
Learn the ropes (10 points)	Complete the Basic standalone tutorial.
Lone Wolf (40 points)	Complete any mission (except The Signal) solo on Legendary with all skulls activated.
Long-term commitment (30 points)	Complete at least 1 Weekly Challenge each week for a month.
Making the most of the day (10 points)	Complete 3 Daily Challenges in one day.
Meat grinder (20 points)	Kill 100 infantry with anti-infantry units (Multiplayer, Skirmish or Blitz).
Morbid curiosities (20 points)	Collect half of the Skulls.
Natural intelligence (10 points)	Play a Skirmish match alone against only AI opponents (1 or more).
On fire (20 points)	Score 500,000 points in a single Blitz Firefight.
Overkill (30 points)	Destroy 500 units with Leader Powers (Multiplayer, Skirmish or Blitz).
Paint it red (10 points)	Achieve the highest possible kill-streak in any Blitz mode.
Palmer's Pure Gold (30 points)	Earn a gold medal on every mission (except Prologue) on any difficulty.
Sentinel size matters (10 points)	Complete The Halo.
Short-term commitment (20 points)	Complete at least 1 Daily Challenge each day for a week.
Space Healer (30 points)	Cast 100 Healing Leader Powers (Multiplayer, Skirmish or Blitz).
Spare change (10 points)	Spend 5 Leader Points in Multiplayer or Skirmish.
Stacked the chips (10 points)	Gather 150 Energy Crates over any number of Blitz matches.
Stirring the pot (10 points)	Complete The Cartographer.
Surviving the long war (60 points)	Complete the Campaign on Legendary.
The Scrappy Six (20 points)	Complete a Multiplayer match as each of the 6 launch leaders (Matchmaking only).
The hand that feeds (20 points)	Kill a unit owned by a developer or someone who has this achievement.
The hard fight (40 points)	Complete the Campaign on Heroic.
The rank and file (10 points)	Recruit or construct 1 of each UNSC unit in Multiplayer or Skirmish (Launch units only).
The setup... (10 points)	Complete Hold the Line.
The tribe (10 points)	Recruit or construct 1 of each Banished unit in Multiplayer or Skirmish (Launch units only).
This war is over (30 points)	Complete the Campaign.
Trash compactor (20 points)	Destroy 100 vehicles with anti-vehicle units (Multiplayer, Skirmish or Blitz).
Two heads are better than none (10 points)	Win a Skirmish match with a friend against only AI opponents (2 or more).
Two heads are better than one (10 points)	Complete a mission in co-op.
Wake up (10 points)	Complete The Signal.
You've got a case of the Birley (20 points)	In a 1v1 Skirmish against Legendary AI, recycle your base in the first 5 minutes and then win.