The setting of Dead Space is the Ishimura. A ship that is like another character in game. And like all characters in Dead Space they become changed by the marker.
As the player progresses the ship becomes more warped and more disturbing as the game goes on. Similar to a human changing, when in proximity to a marker, the changes start small but ramp up to full blown horrific physical changes.

The transformation of a ship... into a beast. This video looks at the necromorphization of the Ishimura. Enjoy.

Dead Space Lore.