"Earth," 2020.
An alien race invaded, decimating everything in their wake.
Tall black towers sprouted in the center of all major cities, emitting a signal called The Noise. It affected every human being, and those over the age of 25 succumbed to its call and became mindless vessels, walking towards the nearest black tower. It was not an instantaneous reaction, but one that happened as the years passed; days became months became years, and there were less and less adults in the world. Those that were unfortunate enough to turn 21 began experiencing the pull of The Noise on their mind -- no one could resist. People found that those born after the invasion of the aliens were born with the curse as well.
Not only did the aliens bring The Noise, but the animals were affected, morphing into something more frightening, more powerful. Items called Minerals began to show up, gems with special powers engraved in them. No one knew what to make of these phenomena; no one knew how to use them.
"Earth," 2023.
A group of adults, 67 years old, struggling with the pull of The Noise, made a discovery of how to utilize the minerals. It was almost as if they were magic, energy sources trapped in the shines of gems that had the potential to rebuild society -- and maybe even overthrow the aliens. Regular weapons didn't work on the extraterrestrials, but they were sure that the Minerals had some sort of secret to be uncovered, some sort of code that needed to be cracked, and all of its energy and power would be unleashed.
"Earth," 2024.
With the help of the dwindling adults, several cities began to rise from the ashes of the old world to serve as refugees for the kids.
Children had to grow up faster. They began to adapt to the new world, to read books written by great men, to learn from the dying generation before them. They had to kill to survive, discarding part of their humanity, destroying their own innocence to obtain a different part of their nature that would never have awakened had the earth not be forced into their hands.
"Earth," 2026.
The aliens did not interfere with the construction of the refugee cities until now. The first attack was on Lacuid, coming from the caverns below it. The other three cities reported the aliens attack weeks later, coming from underground, too. Ever since then, attacks have happened more frequently, and the only attacks coming from above ground would be during the days of the equinox.
The aliens did not attack to kill, but instead, seemed to desire injecting the kids with some sort of sedative secreted from their scythe-like arms. They wanted survivors.
"Earth," 2029.
The last adult of The Old Age entered the black tower, a man named Neil Middle, age 48.
The kids now controlled the earth.
"Earth," 2035.
Present day.
In The Underbelly of Lacuid, Squad 2 was on the last day of their tour, fending off a twelve day attack from the aliens. Abruptly, a bright light appeared, blinding everybody. When the light vanished, in its place were three kids, dazed, confused, and in the middle of the bloodshed.
Two aliens darted for them, their claws ready for the kill, when Rubido rushed forward with his gun and sacrificed himself to save them.
It was at that very moment that The Travelers made enemies -- they were strangers that had caused the death of a beloved comrade.
"Get them off my ******** battlefield!"