The 'Inside' soundtrack was created with a human skull

No wonder the game is so creepy.

Inside, the mysterious puzzle platformer by Playdead, continues the dark and isolating tone of its predecessor, Limbo. Much of the game's atmosphere can be attributed to the soundtrack, which offers a beautiful, yet haunting frame for the narrative. To nail this sombre mood, composer and sound designer Martin Stig Andersen turned to the human body. He found an old skull (yes, a real skull) and played the game's score through it, like an old school filter. The results were "quite bad," but Anderson persisted -- with a little post-processing, the final tracks were born.

"Every time I start on a new project I really want to find some kind of distinctive, original sound," Anderson told Gamasutra. "Not like a musical style, more like a sound quality that you can associate with that project. I think it helps to create a sort of holistic, whole experience." The human skull created an "iconic signature," Anderson argues, which would have been difficult to replicate with muic software alone. The teeth, for instance, made small vibrations that should sound "unsettling, but also strangely familiar" to the player. Overkill? Maybe, but Anderson says such a "detour" can be necessary to create something truly new and unique.