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Nightmare Fuel: XCOM: Enemy Unknown
Remember those Mutons and how they're supposed to be the front line troops for the invaders? They can take some serious punishment, soaking bullets to the face, to say nothing of their elite counterparts. Now, let's go to South America's continent bonus, "We Have Ways", which allows all interrogations and autopsies to be completed immediately. Just what are they doing to the Mutons to make them talk so fast?
The Terror missions. You hear screams and panicking in the background while you're attempting to rescue an isolated group of civilians, who are being picked off one by one by aliens. They're also probably going to be the first time you'll meet the Chryssalids. Huh? They killed a civilian, you say? What!? THE CIVILIAN IT KILLED CAME BACK TO LIFE!?
The tutorial, if you played the first game when you see the soldier in the warehouse, you just know he is gonna frag you, and there is nothing you can do to keep yourself from dying.
Ethereals. Sectoids and Sectoid Commanders can pull off some pretty nasty psionic moves. With Ethereals, this is all they do. One Ethereal, and your squad goes from a highly disciplined team armed with high-tech weaponry to a terrified group, cowering from psionic attacks and the weapons of their their own comrades suffering from the effects of Mind Rape.
The News Ticker in the Situation room will paint a very grim and bleak picture if you're doing poorly against the aliens.
One of the Vendor Trash that you can collect after capturing the alien base is the "Alien Food", a nutritious slurry eaten by the aliens. The description reveals that the soup contains unmistakable traces of human DNA. With that in mind, just think about what happens to all the civilians that gets abducted, or the unpleasant implications on what will happen to the body of your fallen soldiers if you are unable to retrieve them due to the mission being aborted.
Site Recon. It's a Council Mission in Enemy Within where the team is dispatched to investigate a distress signal from a Canadian fishing village. The regular military rescuers have gone silent. You land at the village and start to progress through it. Then, zombies start popping up. This looks bad, because where there's zombies, there's Chryssalids. You push through the village, to find a wrecked whaling ship, where the sharks and a captured whale are being used to incubate an army of Chryssalids. And more and more are getting birthed every round. Central makes it clear that you've only got one option: fight through the horde of Chryssalids to activate the boat's transponder so XCOM can direct an airstrike to wipe out the entire village. Then, once you've managed to pull that off, Chryssalids start pouring out of the whale-hive, and you've got to make a mad dash back to the landing site before either the airstrike wipes you out, or the Chryssalids catch up....
While the surgery isn't shown, MEC Troopers giving up their arms and legs, along what appear to other parts of their body, is horrifying to picture even if it is voluntary.
Also, their voices. MEC Troopers speak in a borderline Creepy Monotone with a filter effect that makes their voices sound computer synthesized. Makes you wonder how much of their humanity they traded for an arm-mounted flamethrower.
While the description is probably meant to be hopeful, the fact that the base augments (the skeletal limbs that the MEC Trooper wears while not in an MEC) are intended to "hopefully" allow the soldier to return to a normal life if XCOM wins the war, is kind of frightening. It's a case of technology and necessity outpacing long-term considerations: MEC Troopers will never be human again, and it shows.
MEC Troopers are unable to be deployed onto the battlefield without their actual MECs, even though they always have a set of arms and legs available. The given reason for this is that the cybernetic arms and legs made for off-duty hours aren't agile enough to be used. Think about that for a moment. Normal humans can certainly go off into battle, but MEC soldiers without their suits can't. As powerful as the suit may be, a MEC Trooper is even less capable than a normal human without it.