Dead Space is what I like to call . . . a cramped universe, it is a universe like doom, resistance, red faction, or the blade films. It has no aliens, it actively destroys worlds, and humans are not extremely varied. Thus there are a limited number of stories that can be told!
This isnt a bad thing, and I am about to explain why dead space has the greatest storytelling engine of all these types of universes.
It breaks down too two factors, human coverup, and marker induced insanity.
The way the markers and humans function in this universe, means that no matter what continuity errors exsist beetween the works. They can all be part of the same universe, any continuity errors easily attributed to the insanity of the characters or the coverup by the government!
The animated films are a great example, continuity errors between those and the games can incredibly easily be attributed to the . . . rather blatant insanity of the characters.
Thus these attributes allow a cramped universe a greater diversity of storytelling opourtunity.
Truely Dead Space is the best at what it does