When talking about Dead Space 2, I mentioned how it focused more on cinematic action when compared to its predecessor. Dead Space 3 turns that evolution up to eleven and goes all-out on the bombast. With the addition of (among others) co-op functionality, microtransactions and weapon crafting, Dead Space 3's kitchen-sink approach waters down the constituent elements that made the first Dead Space stand out from the crowd. While at times an entertaining shooter in its own right, it has been transformed to exactly that: a shooter.
Dead Space 3 actually does a decent job of tying up all the loose ends of its overarching lore. Dead Space 2 muddied the waters when it changed the way Markers work and the third game handwaves this pretty poorly by indicating that each Marker is uniquely sentient and does what it wants. Still, now it's revealed exactly what the Necromorph infestation is and how it propagates (which is explained in greater detail here).
Shame it's pretty much the same galactic threat as the Reapers from the Mass Effect games. The Reapers and the Necromorphs are both ancient races that send out artifacts (mass relays and Markers, respectively) which guide and influence the development of space-faring species so they may be consumed when they're at the peak of their evolution. This makes them both out to be Lovecraftian Great Old Ones. The main difference is that the Reapers preserve the species they assimilate while the Necromorphs are just hungry.
So the macrolevel story does check out reasonably, but its implementation on a microlevel is haphazard at best. The main problem is the addition of John Carver as a secondary player character to support the added co-op functionality. His presence does make sense from a narrative point of view. I've talked before about how Isaac's profession as an engineer doesn't really inform the way he carries himself, as he turns out to be a more effective one-man-army than the actual army. But he's still an engineer and everyone treats him as such. Sending him out with a professional soldier at his side is a sensible tactic.
That's the narrative side of things, but the way Carver is inserted into the gameplay makes me think that the decision to turn Dead Space 3 into a co-op game was made fairly late in development. Isaac is still very much the focus, as all the cutscenes aim the camera squarely at his face. Whenever a cutscene ends for those playing Carver, the camera still pans to Isaac's posterior before quickly shifting, as if to say "Oh right, I'm following this guy." The game even ends on Isaac wistfully staring at a photo of Ellie, while Carver was unceremoniously whisked from view moments earlier, never to be seen again. The Awakened DLC does bring him back, but the ending to the main game should stand on its own. For Carver, it does not.
It gets worse when the game is played in singleplayer. Rather than have Carver be controlled by the AI (which is asking for trouble, unless you're Ken Levine), he only shows up in cutscenes and is absent during gameplay. He presumably finds a different route every time. This means that he just sort of sticks his head in the door now and then to see what's going on. His character arc is also completely lost, which makes his sudden bout of introspection towards the end all the more jarring. He solemnly asks Isaac whether he's a good man, but the two haven't forged any kind of bond that would allow for a decent answer.
As a result, Dead Space 3 doesn't fare well as the co-op action shooter it turned out to be (or was turned into, as the case may be), which is reflected in the Short Script. Incidentally, this is the third trilogy that has now been completely abridged on this site (after Mass Effect and Deus Ex). I'm now playing my way through BioShock Infinite, which will mark the fourth. That game's Short Script is going to be a tough nut to crack, though. The game's just so damn good!