Crysis (series)/WMG

The nanosuits are built on alien technology.
Let's face it, they're way way way more advanced than anything we should have at that point in time. Plus the game calls most alien enemies "exosuits", explicitly claiming they're some kind of ubersuits piloted by the fish-like aliens we see inside the starship. Hum, reminds me of something.
 * The setting takes place in 2020. Furthermore, we are already developing cloak technology and have already started with a few prototypes with powered exoskeletons. Of course, if you are "one of those," you could always say the computer chip came from an alien crash back in the 50s and bunk the whole thing...
 * The aliens using exosuits is not just a claim. If you look at the alien "invasion force" in the Core level of Crysis, you see the aliens actually go into the machines. They got the knowledge from Nomad's video feed.
 * Confirmed;

The "Aliens" are in fact robots who will take over the world and create the Matrix!
The squiddies look almost identical to the exosuits worn by the aliens, and the aliens could actually be made up of nanites. Plus, they seem obsessed with the color blue, and everything in the real world of the Matrix films has a blueish hue.

Prophet is an alien, but not one of the "bad" aliens.
Prophet, as he is shown, is remarkably cool throughout the entire game, displaying little surprise when encountering the frozen ship and more or less none when dealing with the aliens. Moreover, he reverse-engineers an alien weapon in the field in less than a day; the engineer aboard the Constitution claims that that's more or less impossible. He also knew that a nuclear warhead wouldn't be enough to stop the aliens--an observation that hadn't yet been made when he returned to the island. It makes sense to think (or, at least it does on the WMG page) that he is in fact a member of an alien species-- likely one that's at odds with the Cryaliens--and simply masquerading as a human. For all we know, he might've invented the nanosuit, either directly or indirectly.
 * Jossed;

Crysis was made using reverse-engineered alien technology.
And that is why your brand new 4Ghz gaming rig can't play it.
 * Mine can \o/

The Ceph in Crysis 2 are a different "nationality" that those from Crysis 1, which explains the differences between the two.
Like humans, the Ceph have different "races/nationalities". Each Ceph mothership is crewed by a different "nationality" of Ceph. So, the Ceph in the first game came from the Lingshan mothership, were blue, and used floating squid-like exosuits. Meanwhile, the Ceph in the second game came from the New York mothership, are red, and use bipedal humanoid exosuits instead. Similar to how U.S. military hardware is different from Russian/Chinese military hardware.
 * From a certain perspective, this might be true. The Ceph have adapted every aspect of themselves to efficiently combat humans in their own environment. This includes the organic individuals piloting the exosuits & vehicles. One could say that - in a sense - they've become a whole new species.
 * I agree with the subspecies/nationality theory. The similarity in strategies (using an ice-sphere or bioweapon to kill people around them and then fortify their position) and the presence of lithoships all over the planet makes it very likely that this is the case. The "adaptation" theory is only marginally more unlikely.
 * Alternate possibility; the color change is what happens when the Ceph leave their normal climate of "really friggen cold" and walk around in human-habitable temperatures.
 * Legion indicates that the Ceph were adapting and changing after being reactivated.

The color scheme of the Ceph in Crysis 3 will be yellow.
Or green, depending on which kind of primary colors are chosen.
 * Seconded! Either that, or we'll be seeing an army of mixed units.

The nanosuits actively control the perceptions of the people inside them.
This would explain at least some of the differences between the two games, and opens the storyline up to even more possibilities than before. Nomad might not really be the stoic he seems in the first, if the suit slowly takes over without the player realizing it. By the time of the alien ship, it's the suit talking, not Nomad. This also allows for Prophet's claim that the burning of Jester and Aztec was done by the suits themselves. They might have just created a false broadcast from Prophet to cast blame elsewhere. Whether it was really the suits "using" their hosts up, or Prophet being freaked out and claiming that, I can't tell. There's the possibility that the suits form an attachment to their hosts, and when the host dies, the suit commits suicide in shame or sadness at the loss of their partner. Of course, there's a long distance between simply being alive and having emotions, but when an organism stays in contact with an emotional being long enough, it can grow with them. The reason Prophet's suit didn't burn up was because the 2.0 suits can back up a person's neural network, apparently, and Prophet's suit had a blank slate in the zombie Alcatraz. All sorts of fridge horror, or awesomeness, when you look at the games in this light.
 * Going deeper with this, a few times in Crysis 2, after taking a cinematic death, the player gets the quick-time demand to use a defibrillator on Alcatraz, who's heart has stopped beating. So this makes me wonder, are we playing Alcatraz, or are we playing as the suit? Alcatraz would be unable to revive himself in such a manner after his heart stopped...

In Crysis 2, you aren't Alcatraz; you ARE the nanosuit.
You're only Alcatraz in the first level. In the sequences where the suit is off, you can't control Alcatraz. And exactly how can one use a defibrillator on himself?

The nanosuits are repurposed and reverse-engineered from Asura Machina from Asura Cryin into a personal suit.
It explains how the users are granted super strength... at the cost of him/herself. Sometimes after the events of Asura Cryin, the Asura Machina fell into US hands and reverse-engineered into military personal suit...

Alternatively, the nanosuits and Cephs are one of the ways the Incubator harvest energy source
In an alternate universe, the Incubator manifests as Dr. Hargreaves and reverse-engineering nanosuits, which incidentally also gives superpowers and eats the body and soul of the user, just like the Soul Gems did.
 * Hargreave even admits to being economical with the truth, which is exactly what Incubators do.

The freezing in the first game was caused by heat leeching
The aliens had no particular interest in making the island cold. Everything freezing over was a sideffect of them draining the heat from the area to power up the systems of their ship. This is why the nuke launched at the island was an especially effective way to make them stronger.

The Ceph and the aliens from the first game are not the same race
Think about it. The Crysis 1 aliens and the Ceph are styled completely different than each other. The whole "adapting" theory also doesn't make sense because the aliens would have probably adapted once they got to earth, which was before mankind was even around. It would make a whole lot more sense and would be pretty interesting if the Ceph and Crysis 1 aliens were different species and possibly fighting over Earth.

Whoever created the Ceph knew what they were doing - even their non-sentience.
There's a reason we don't fully automate farming - too much chance of false positives and false negatives - abandoning ripe crops whil picking overripe or rotten crops, weeds, etc. What is easily automated is turning over the soil periodically. Look at what they do - they spread a flesh-liquefying plague to destroy mammals, which is collected by the Ticks for disposal, they deploy cyborg weapons platforms with exposed flesh, they rip up landscapes, buildings and streets with buzzsaw-lined giant snakes. Any industrialized race could use hazmat gear to contain the plague, kill the 'borgs with chemical slugthrowers, and flee from the "tower snakes." Any dead-end lifeforms would die and make way for new ones, and the ones with any sense would get off the fucking planet. Where they would expand freely, and be ready to be harvested on a much larger scale - or should I say... Reaped? Hell, even stealing Ceph tech would merely lock them into the Ceph tech tree, causing their civilization to develop along predictable paths.

Dominic Lockhart's dead nephew was
The reason Lockhart believes the Nanosuits are "Abominations" is because his nephew died testing the 1.0 models under "unknown circumstances." If this nephew turned out to be, it would be downright hilarious - didn't die because of his Nanosuit malfunctioning, he died because CIA agent Norman West had one of his torturers rip open his right femoral artery with a cordless power drill. Because he believed that Hargreave was working with the North Koreans, and that Prophet was jerking him around with stories of "aliens". That, and he was pissed that Prophet pointed out that the CIA has about as much "intelligence" as a tapeworm - they missed the fall of the Berlin Wall, 9/11, the Arab Spring, and an equally game-changing Turn of the Millennium event known as "The Darien Resurgence." Lockhart's freakout would thus be added to an already Long List of CIA fuckups.