On DS2 and DS3 apparently, a Marker actually emits waves that causes the necromorph infection.Dead Space is one hell of a game.

In a time where Silent Hill and Alone In The Dead are pretty much six feet under and a time where Resident Evil is more Die Hard than Alien, Viseral games' Dead Space was a breath of fresh air. In case you don't know, Issac Clarke, a former engineer, spends his time running around a now abandoned-of-life mining ship called the USG Ishimura. He battles waves of Necromorphs, monsters created from corpses and an alien virus. On the USG Ishimura, screams of the living have been supplanted by roars of the dead. There a load of religious stuff to do with Unitology and a Marker but that's not important. Curtis, a Unitologist miner, is one of the few still clinging to life within, and desperate to escape. The Marker, however, is not easy to elude. What is important, however, is Issac's loving girlfriend Nicole, who was stationed on the Ishimura before the monsters began their attack. As Issac makes his way through the ship, he begins to see her, but can never reach her.

By the end of the game, it's revealed that Nicole committed suicide via lethal injection before he even arrived and that Issac has slowly been going insane. Well, yeah! But where is the Easter egg? After you finish the game, head back into the chapter select menu and what do you see? That's right. Dead Spaces characters faces are sort of modeled after their voice actors, and IIRC Nicole has a different voice actor in DS2. The first letter of each of the 12 chapters in Dead Space spells NICOLE IS DEAD.

'What was the point of that pregnant pause'. Mind blown, melted, dripping out of my ear onto my controller.

Dead space nicole necromorph