Headcase (achievement)

Headcase is an achievement in Halo 3: ODST. It is awarded for completing any Campaign level on any difficulty with at least one Skull activated. It is worth 5 Gamerscore.

It is represented by an olive green circle with the Marathon symbol imprinted in it, with a skull in front. The skull has glowing red eyes.

Trivia
It doesn't matter whether the player uses Gold or Silver Skulls to get this achievement, for example, the player could get it by only having the IWHBYD Skull activated.