The emplacement turrets retracted, and the Nyx Breaker was underway. This time, it didn't reappear a moderate distance away from where it'd been, and continued in its journey far longer. Though there were two larger Aud rings remaining that encircled the terrain around the Last Light, that didn't say much about the one currently attempting to defile the last bastion of human civilization with their ravaging army.
The first ring was still large enough to close ranks around the Last Light as well, proving to be so massive that though the battle had been raging for a good while by that point, over half the Aud hadn't even reached the killing field yet.
They remained held back from making progress with their superior mobility by the combination of the sheer numbers of their own brethren they had to butt by and bypass, and the distant wall-grade emplacements tearing into their bodies with mechanical cruelty.
And the Last Light, too, was more than a simple city. Something so small and meager could never house humanity's necessary infrastructure. No, the population itself wasn't an issue. They occupied a territory so brobdingnagian and erected walls around it, though living space wouldn't have been an issue even if a virile and healthy human society occupied a territory half the size for hundreds more years.
Humanity needed every last meter not for living space, but for industry. Storage. Facilities. Manufacturing. Communications. Emergent services. Energy. Finance. Agriculture. Government. Public health. Waste management. Transportation. The list went on and on, as did the one secured plot of land left under human control.
But no space was infinite; large to an extent, and no more. The Nyx Breaker crossed one distance marker, then another, then another, closing the distance between it and its newest priority. The drills burrowed further under the chaos and carnage taking place above.
According to the echo room's scans, they had passed beneath the outer face of the walls. It took several seconds for them to leave the inner face behind, too. Re-5 had the piloting crews bring the Nyx Breaker lower, but not halt their forward progress.
She didn't know how stable the city foundations were when exposed to the geokinetic disruptions generated by a Titan. Though the foundations should be rated well enough to withstand the same phenomena produced at a smaller scale by Aud, she would take no chances unless absolutely necessary.
"Can we determine the locations of any preexisting tunnels right now?"
"The engineers are saying we've already broken through a few of them and not realized it, since the echo room doesn't work like a live feed. It takes the returning sensor readings through the legs and overlays them to model everything that sent back the returning echoes. Though it operates fine, what we're doing now was never supposed to be the main specialty of the echo room."
"Stability and precision over quick results while in motion, yes, I know." She shrugged. "We don't have a choice, though. I can order the piloting crews to stop the Titan once right now to do a cursory examination of the ground layers around us, but we cannot do so on repeat after clearing out clumps, then needing a fresh model depicting the movement of Aud. That would be too slow."
"That isn't necessary," he reassured her. "Having the Nyx Breaker move slower when not engaging Aud is good enough. Should any latch on, we can return to a normal speed like before."
"And if any Aud higher than green latches on?"
"You're worried the sitesman's incident will repeat itself."
"Yes, and we no longer have servicemen of his caliber who can remove blues with minimal collateral damage. Should events conspire and advance according to my trepidations, what then?"
"We'll deal with it when it comes to that."
"Not if?"
"Not if. Better to plan for every alternative possible before execution. Besides, we still have plenty of carriers of the Old Man's Blessing aboard. They're dispersed throughout the Titan's length, yes, but they can all converge on any one location quick if the need arises. And they won't work to subdue or kill any intruders without aid from the WAV pilots." He hesitated. "If you don't mind me saying, sir, that was foolish on Ze-4's part, to confront a high-tier Aud without reinforcements of any kind."
"I know." She paused their conversation to give the necessary orders to the piloting crews. She decided their primary priority was to increase their visibility, even if the Titan's mobility suffered. The Nyx Breaker slowed, while those staffing the echo room found, to their delight, the models their equipment generated became clearer and more accurate, also increasing in range. "I was thinking the same thing."
The first Aud the Titan encountered was yellow, appearing as a distant speck at the edge of the most recent navigation model. When they traveled closer and it fell within the range of the fur scanners, it illuminated and expanded, becoming yellow.
"We have two methods of attacking them," her officer was telling her. "With our emplacements retracted, we can either ram into any Aud we locate, or traverse around them, disrupting the local stability of underground earth layers enough to cause a collapse, bringing down a good weight upon them. They might even get displaced lower, resetting some of their progress."
The first method held more inherent danger, involving physical contact between the Titan and every Aud its crew located. It would work up to green.
Yellows and below would die outright due to the combination of mass and speed, while greens, capable of surviving a direct impact and even sustained burrowing action, would be so crippled in the aftermath that they would do little else aside from die and find use at their brethren's claws.
But blues, as proven by what happened leading up to Ze-4's incapacitation, could take whatever the Titan could ram into it, and then some. Purples? They hadn't tried, and she suspected that if they did, it would be the purple ramming the Titan, not the other way around.
The second method involved less personal risk for the Titan's crew at the cost of killing efficiency and environmental damage. The chance for yellow furs to die from the crushing weight of tons of rock and sediments wasn't necessarily lower than the other option, but it left open a few loops in physics that the Aud could survive at higher rates using.
And there was another, related risk too: destabilizing the ground underneath the Last Light's foundations might have disastrous consequences for the city, even if the Fifth had recently applied an unimaginable amount of resources to strengthen them against Aud interference or intrusions.