City-states.

[Rebel Fighter]

Our spies have discovered Brazilia is constructing Mecha-elephants to defeat our armies in battle.
-Terraform some mountains on our border with Brazilia, that should stop 'em...

This needs to be a unit!

 

[Darsnan]

Any word on them returning in Beyond Earth? I just can't imagine how would they be implemented on an alien planet, which worries me because they're a fantastic mechanic.

When I was playing around with Civ 5 I created a little exo-planet sci-fi mod where I imagined the C-S were the remnants of an ancient alien civilization called the Sthl. Some catastrophe had befallen their planet-wide civilization, and the only cities to survive were those protected by Giant Death Robots, which I called Shiva. This is what I imagined it would be like meeting a Shiva (and the Sthl) for the first time in game:

Spoiler :

A report from one of our scouts, showing us we are not alone on this world:

"We could feel it first - a dull thud.....thud.....thud slowly moving closer, before finally the monstrous machine came crashing out of a nearby glade and into view. Five stories tall and armed to the teeth, it appeared every bit as lethal as similar machines humans had designed for combat purposes on Earth. But what stood out about this machine was its apparent antiquity: even from our distance we could see the machine had been repaired a number of times, several of which were poorly done. And as the machine pivoted and moved towards us, we could tell that it was actually limping."

"We're being scanned", a tech added

And as for the Sthl cities which didn't have Shiva? These were the Ruins and barb camps which dotted the landscape. The barb camps were actually cyborg processing centers that I called Wraith infestations. Here is what I imagined the text would be like for clearing a Wraith infestation:

Spoiler :

In an unusual breach of protocol one of your junior staff – the one responsible for coordinating scout exploration, burst into your staff meeting. “Consul, I think you need to see this now”.
You look onto the face of your subordinate and see a look you have never seen on this man before – a haunted, disturbed look, and realize that whatever it is, it most certainly takes precedence over the current affairs you are presiding over. You nod ascent to the man, and he proceeds to pull up a holo-link from one of your Long Range Patrols.
The combat team had just eliminated a Wraith unit which seemed to be defending one of the ancient cities which dotted the landscape of this world. Upon exploration of the ruins the team found a large tunnel which proceeded down into the catacombs below the ancient city. With weapons ready, the team descended into the cavernous bowels.
As the team descended further an eerie hum became discernable, and a green artificial light illuminated the way. The cavern gave way to what could only be described as large compartments, each one linked by sliding doors. In the first compartment the stench of rot was overpowering, and as the team reached the far end of this room the doors automatically slid open to reveal the next room, which could only be described as a visage out of a horror movie: hung from the ceiling were what at first looked like rows upon rows of carcasses in a slaughterhouse, however only after a second was it realized these were human bodies: armless and legless and with some sort of machine growing into their skulls, the bodies were barely recognizable as human. On one the tattered remains of a uniform still clung, and on close-up an emblem became discernable over the bodies heart – “Colonizer Team 5”.
And then we saw one of the bodies twitch. “Their alive!”, one of the scout team exclaimed into the feed.
The combat team’s medic moved up and examined one of the victims. Through the medic’s helmet cam you and your staff could see the cables suspending the bodies contained fluids and electrical wires, and that these were connected to various portions of the bodies: these people were being kept alive by artificial means! The medic turned the victim’s head to reveal the machinery which was implanted over the frontal temple of the skull, “it looks like a full lobotomy has been performed, and the frontal lobes replaced by this machine”.
The team moved on to the next room, which contained even more bodies hung from the ceiling. Only in this bay prosthetic arms and legs had been attached to the victims stumps, and other machinery added at various portions of the body.
“it’s a Cyborg Factory”, someone - Dr. Richtoven by the sound of his voice – exclaimed, “an ancient cyborg factory”.
“But something went wrong”, someone else said into the silence.
“Horribly wrong, yes. Either through an inadvertent programming bug, or a malignant virus introduced by an enemy, this facility went from repairing injured soldiers, to harvesting whatever bodies it could capture, and producing more armies of mindless automatons.”
The vision painted by Dr Richtoven was that of a nightmare scenario: legions of mindless automatons rounding up helpless civilians to “process”, producing even more armies of the undead, who would complete the cycle by going out and rounding up even more helpless civilians. If enough of these cyborg facilities on this planet had malfunctioned like this, it could very well have spelled the end of civilization on this world!
In silence the combat team finished their tour of the facility, the remaining bays they proceeded through being empty until the last one, where stores of weaponry were stacked against the walls. One could almost envision the newly activated cyborgs picking up their weapons and proceeding off the assembly line directly to the attack.
The Team Leader turned to the holo-pickup, “What should we do, sir?”
The answer was easy. “Salvage anything you can, then incinerate the rest of it”.
After the feed went dead you turned to your staff, “I want copies of this holo sent to all of our scout teams. Make sure they understand what it is they are up against, and what will happen to them if they are captured by these Wraith”.

And here is the text I imagined for when you "captured" a Wraith unit from a destroyed infestation:

Spoiler :

The hologram of your senior military liaison was waiting for you when you entered your office, “Consul, I have a request to ask, which I believe only you can answer”.
It was unusual for your military’s leader to approach you with requests, especially as a hologram: typically the man was a flesh and blood type, very up close and personal. For some reason the man didn’t want to be seen entering your office at this moment: it appeared as though he wanted this conversation to be “off the record”.
“Yes, of course”, you proffered a chair to the man – no telling how long he had been standing at the hologram pick-up, waiting for you to arrive.
The hologram seated himself into a chair which appeared on the pick-up, and you seated yourself as well. The man fidgeted, seemingly trying to assess your mood, before proceeding, “Consul, one of our military units has captured a functional Wraith unit.”
“Functional?”
“Yes, sir, armed and ready to go. Our scout team captured what appears to be the controller for this Wraith unit, and we have experimented enough with the controller that we can give the unit basic orders such as where to go, to dig in, even to fire their weapons at specified targets”.
“Well, bring that abomination back to our research lab so our techs can tear it apart”.
Your military liaison moved uneasily in his chair before leaning forward and coming to the point, “Consul, I’d like to employ the Wraith unit on our front lines. You’ve seen how Wraith fight – they are completely fearless, and will attack anything. I think they would make ideal shock troops, which would then save the lives of our own troops”.
You lean back in your own chair, absorbing the shock of words which have just hit you. This Wraith unit, which had once been human beings like yourself, never deserved to end up as automatons, and to employ them as shock troops against enemies – what would people think? Would you yourself, if captured and “processed” b y the Wraith, want what is left of your corporal body used as cannon fodder? Or would you want your body destroyed, which was the only alternative currently available? And as the general said, using these abominations as shock troops would indeed save the lives of your own soldiers. No wonder the general wanted this conversation “off the books”!
“Please leave me”, you say, and the general’s hologram obediently blinks off. You sit in your seat thinking for several long few minutes, knowing that indeed this is your decisions, and yours alone. Even your holographic Advisor suite has shrunk from weighing in on this decision.
Finally, after weighing the options, you make a decision and call up the general. His hologram reappears, and with weighted words you respond, “General, this is what I want you to do”.

So I think there are some options out there as far as jimmying in the C-S mechanic into BE.

Below are some pics from the Sthl cities and Wraith infestations I took while playing the mod: