Okay, so hear me out.

(Very minor Dark Souls spoilers follow.)

You all know Dark Souls by now. Y'know, the game where you play this undead person trying to do some stuff that's supposed to fulfill some prophecy in an area where there's nothing but undead.

So everyone's undead there, pretty much. Everyone's a zombie.

One area in particular has you fighting ghosts instead of these zombie-people. Now, if we assume that the undead rule was in effect before they all got turned into vengeful blade-armed ghosts that like to hug you and bite you, then what are they?

They are zombie ghosts.

In Dark Souls, you can get afflicted with a Cursed status. That status leaves you at half HP...

Or, half life.

One way to get rid of this status is to go see a guy who's deep in zombie ghost territory. He will be able to restore you to full HP.

Or, full life.

In conclusion:

In Dark Souls, Half Life + Zombie Ghosts = Full Life Consequences.

(Dark Souls images courtesy of the Dark Souls Wikia.)