Halo 3 skulls

An example of a skull in Halo 3.

Skulls are a series of gameplay modifiers available for use in Halo 3 and Halo 3: ODST. Both games feature the same roster of skulls and effects, though in Halo 3 these items are hidden throughout the game's campaign as hidden easter eggs - and must be found before they can be used. In ODST and the Halo: The Master Chief Collection iterations of both games, all skulls are unlocked from the start.

Once activated, a skull makes gameplay either more humorous, or more challenging.

Background

The skulls greatly resemble those in the Multiplayer game variant Oddball, and can be used as weapons in much the same way. However, they lack the information text (i.e. "Press RB to pick up...") to pick them up. They are usually hidden and out of the way, so one must thoroughly search for them, or know where they are, to get them. There are thirteen skulls in Halo 3, along with a fourteenth secret skull on Cortana.

To unlock a skull, you must start its level from the beginning, on Normal or higher. You can stop playing at any time (provided you resume using the "Resume Solo/Co-op Game" option from the main menu), and you do not need to carry the skull all the way to the end (with the exception of the IWHBYD skull).

The Mythic skull is the only skull available on Easy, although you will not receive the achievement for it. Also, a very important note is that the skulls are affected by physics. This means that, with the exception of the Famine skull, skulls can be moved by grenades, explosions, and other forces.

Once a skull is unlocked, you can activate it from the Campaign Lobby. Simply press X while in the Campaign Lobby, and then select a skull with A to activate it. Multiple skulls can be activated at once.

There are two different types of skulls: Gold skulls and silver skulls. Gold skulls will, when unlocked, grant you achievements, each worth 10 Gamerscore; when activated, they add multipliers to your Campaign Meta-game score. The nine gold skulls affect the difficulty of game-play, making the game more challenging. Silver skulls do not unlock achievements or add multipliers to your meta-game score. They are differentiated on the selection screen by their color, but are identical in-game. There are five Silver skulls, and four of them affects the physics, dialog, and appearance of gameplay.

Collecting 5, 9, and all 13 skulls of either type will unlock the Hayabusa Chest, Shoulders, and Helmet Armor Permutations, respectively, for usage in Multiplayer and Matchmaking.

In Halo: The Master Chief Collection, the functionality of Halo 3 skulls is identical, with two differences. All skulls (and Armor Permutations) are unlocked for gameplay from the start. The skulls can still be found and collected in campaign for achievements: both gold and silver skulls unlock achievements worth 5 Gamerscore each.

Campaign skulls

Meta game quick reference

Icon	Skull Name	Multiplier	Short Description
	Iron	3×	In Solo play, dying reverts the player to the beginning of the level. In cooperative play, any player death reverts to the previous checkpoint.
	Black Eye	1.5x	No auto-shield regeneration. Only melee attacks cause shields to recharge.
	Tough Luck	1.5×	Grenades, Needler fire, projectiles (i.e. Rocket Launcher, Brute Shot, and Fuel Rod Cannon) and vehicular charges are evaded more skillfully by the AI. Brutes go Berserk more often and Grunts will turn Kamikaze more often.
	Catch	1.5×	NPCs throw many more grenades at an alarming rate. NPCs always drop two grenades when dying.
	Fog	1.5×	Motion Tracker is fully disabled.
	Famine	2×	Dropped weapons have much less ammunition/charge.
	Thunderstorm	1.5×	All enemies are promoted to higher ranks. (More experience) .
	Tilt	2×	Enemy defensive resistances/weaknesses are amplified.
	Mythic	2×	All NPC's health allocation is doubled.
	Blind	1×	Player HUD and weapon model are disabled.