In Alien Invasion, most of the quotes are fairly campy and B-movie horror- a exterminator complaining they didn't have enough bug spray for the Myrmidons, a rousing speech from a military general and a crazy conspiracy theorist credited as a "concerned intelligence agent" . But the final quote, from a survivor of the Visages?
Nanopocalypse is one of the most horrifying scenarios in the game, period. Virtually everything about it is equally depressing and disturbing:
The cover alone features a man being graphically devoured by the ocean of the titular nanobots, complete with his whole skin melting and his face frozen in a scream.
The very premise of nanobots going on a rampage. They consume everything and everyone they get, they multiply in a rapid succession and they can only be slowed down with harsh temperature. Even that is not much of advantage because, as long as there's the organics to dissolve, the nanobots will come back to life after laying dormant every now and then. The rulebook states that even if nanobots might shut down for good through natural decaying, they will be still consuming the very microorganisms needed for the decomposition process.
The very timeline is short and brutal in describing how fast the wave has been spreading: in less than three weeks, the human race is reduced to less than 20%! The rest doesn't fare much better, as descriped below.
The ending manages to be terrifyingly bleak even by the game's own standards. The last remnants of humanity are trapped on the Nourth and South Poles, stuck in perpetual wars for resources between the research stations and having zero way to reclaim the rest of the planet. An ordinary scientific experiment ends up dooming the entire planet in less than a month, and the nanobot swarm, as terrifying as it was on mainland, is only barely held back by the winter cold. Either way, it's a horrific and tragic experience to go through at the same time; whatever the nanobots will shut down permanently or not, it's now impossible to reclaim the planet and bring life back on it.
The first scenario of the first book, Night of the Meteor, has everyone reanimate when they die, not just humans, but animals too. Rats in particular can get anywhere without you noticing it, and even taking a single swarm down might bring much more. The post-apocalypse is not much better - sure, ghouls are gone for good, but E.D.E.N will watch you under constant check.
The main danger in It Ends With a Whisper is not just zombies themselves, but also the power of Voodoo witchcraft in general. Anyone can be possessed by a Voodoo practicioner and become their puppet, and the only way to bring them back is to either kill the priest responsible for possession or peacefully have them exorcise the spirit from the victim's body, and more often than not the priest is beyond the reach anyway. And that's not to speak of those who have died and renanimated, becoming feral ghouls who can spread the killing curse by biting and scratching their victims.
Under the Skin has this in spades. Not only because the zombies in this scenario are caused by nigh-unkillable parasites that range in size from single-celled microorganisms to towering abominations the size of small buildings, and can infest humans during any of these stages, with the infestation usually not being apparent at first, but also because of the implied Government Conspiracy.
Similarly, Nanopocalypse. Being more than microscopic in size, the nanomachines can get in pretty much anywhere, no matter how tightly sealed, and it only takes one nanobot to infest and replicate in something, or someone.
