All old version RIG suits have spare helmets build in
This explains how a new helmet 'appears' in the add on awakened, it just took a while to get itself together. The new rig versions had the feature removed to reduce cost/weight or Isaac's suit was so banged up by the first crash it didn't work.
Mass Effect
Not only does the Mass Effect franchise still exist this far into the future, it's evolved to become the longest-running continuous work of fiction in human history, with each sequel trying to top the one that came before. At the time the Dead Space series takes place we're on Mass Effect 28, in which the God-General Lord Shepard wages war across universes with his inter-dimensional cosmic battle fleet, fighting to destroy a race of omnipotent Space Angels that threaten to exterminate all planes of existence save their own.
- "Shepard, thy lord and guardian, may thy assault rifle and omniblade give me strength to venture into darkness, to strike those who screweth me over down low, and to assert my dominance on all underlings who giveth me lip, for the dead may not remain dead here in Dead Space, but for you, what else is new, one of such who died to live once again? And when the dark things come out en masse, and I am surrounded by enemies, I shall smile and remember, 'I shall not go alone, for I brought the Cain,'. Boomshaklaka-ta-da!" - something that would be muttered during a final stand in Dead Space.
The ending that completely defeated the purpose of Dead Space 3's ending, and the fact that Isaac and Carver survived at all could mean the DLC is this. After all,
the Brethren Moon didn't have time to wake up its siblings, the FTL drive could not have possibly worked in that ship, and there's no way at all either of the main characters could have survived the Moon Drop. Maybe the whole thing is Isaac's mind, dying, tried to come up with a better alternative to his death to make it better. It's only due to Isaac's traumas and broken hero status that the last refuge from death was so horrifying in itself. Alternatively, it's just all a cash-grab by EA that doesn't need to make sense, as it accomplished its goal of making money.
If not for Series Existence Failure Dead Space 4 would have gone like this.
Isaac and Carver
find the sol system being ripped to shreds but humanity existed way longer then the markers usual strategy would allow thanks to the Tau Volantians. It isn't much but they no longer occupy just the one world which gives them the unexpected time for some of humanity to escape, primarily engineers like Isaac with the CEC who were already in space or other people on ships who wouldn't be in the line of fire from the moons or released markers.Isaac manages to bluff well enough, with Carver's help, to convince the masses he has a plan and to follow him out of the system in effectively a massive convoy of refugees. The co-ordinates Carver gave Isaac in that mostly on the spot speech weren't anything special just an otherwise abandoned Earthgov facility in another solar system but it's a start. A bunch of the refugees get dumped off there to hide and hopefully rebuild sooner or later.
The Bretheran Moons though aren't willing to let any part of humanity escape even if they got their new member from earth and satiated their horror hunger on the colonies. Isaac is better able to resist and see through their manipulation the second time around but it's still enough to give him massive debilitating headaches at range. But Isaac actually comes up with a plan, the mothballed but otherwise still completely serviceable planet cracker fleet.
In a twist of fate the Brethren Moons markers enforcing that consumerist mindset to drain our planet of resources making the markers a necessity gave us exactly the tools to kill the moons. Humanity was never supposed to exist as long as it did after all nor was it supposed to develop so far. Through one means or another Isaac ends up at the controls of the Ishimura again and manages to delivery a breaking speech to the moons while they bombard his mind. Something to the effect of "you think it's okay to consume us, rip our bodies to sheds? Lets see how you like it' followed by that oh so familiar digital voice 'Initiate Planet Crack" and the psychic screams of an elderbeast as it's brainstem is ripped out by gravity tethers.
So at the end Humanity isn't an out and out victor in a case of broke your arm punching out cthulu but they're alive and the Breatheran Moons are forced into retreat after being confronted with death for the first time in eons. While Isaac started out a terrified nobody desperate to save his own ass somehow through his own cunning he managed to turn the tables on an unimaginably powerful monstrous race. Satisfaction achieved.
Ellie is immune to the Marker signal madness.
Like
Lexine Murdoch, but without the ability to stave off Markers' effects on others like Lexine can. Ellie understands the effects on people but doesn't fully comprehend just how taxing the visions are (like Isaac) or how they can subtly alter someone's personality to bring out their worst traits (Norton.) This is why she comes across as demanding and unsympathetic at certain points towards Isaac and doesn't notice (or tries not to notice) Norton's
Motive Decay; much like understanding mental illness in
Real Life, even the most sympathetic individual can grow aggravated when dealing with someone who is suffering from something that is "all in their head." Add the fact that the Necromorphs and Markers are actual tangible threats that Ellie can fight and she sees the people around her responding to the stress of their situation without factoring in how the Marker signals are affecting them. The fact that Isaac can fight off the madness when pressed probably doesn't help, either.
