For example, our character begins the demo totally out of ammo. As he creeps through the corridor, he reaches an open area containing a fresh corpse. The denizens of Rapture are dependant on Adam, a highly valuable substance that can be extracted in raw form from the dead bodies of people who lived in the city. This makes the corpse a target, but also a helpful tool.

Further in and our character runs into a vicious, ceiling-crawling nasty - the result of someone ingesting too much Adam and mutating. With no ammo it's time to backtrack, and as he passes the corpse our character hears heavy, clomping boots hitting the metal flooring. A Protector is coming.