Black ops 2 Nuketown zombies extra song.

This song change is quite simple get the Nuketown population down to 15 by killing zombies and the clocks time above it will make it say 115 and this number has a back story in the game and is the element that is added to guns when you Pack-a-punch them.

Then open this door and walk through and collect the item bellow,

And then the song should change.