Stencil stared at the humans that climbed the tower. For the first few years, they remained on the first floor, content with living there. After all, having lived through World War Three, they wished to stay away from fighting as much as possible.
But of course, they couldn't entirely do that, for living there meant they needed resources. And only coins purchased the necessary resources, including food and water. Completing trials was the sole way of accumulating coins.
To survive, they needed to fight. But during the initial years, everyone only fought the bare minimum. They also had a collective sense in the city, for there were just six million of them left.
The collective community was pretty cohesive. But, it only lasted so long. Eventually, healthy survivors fell in love and had kids.