A world in which going outside could mean death
The streets, once glowing with life and nearly brimming with people using all methods of transportation, stood empty. The dust and sand typically kicked up by the activity lay still for the first time in years. Stray papers skidded across the ground with the slightest breeze. They had been long abandoned. The once white paper yellowed and creased with age. The edges held small tears, loose fibers balled up and clinging futilely to the rest of the pages.
Everyone had disappeared at once. Anyone left outside had been wiped away overnight. Those inside refused to leave. Anyone that had gotten impatient or worried for their missing loved ones left out of desperation. They never returned. There was no sign of them having ever leaving their shelters. No one ever saw what wiped out the people that weren't indoors. No one ever survived to tell the tale.
There were no methods of communication between the survivors. Phone towers had no one left to man them. No one could leave to deliver any written correspondence. For a few days after the outsiders vanished, the internet, power, and TV remained live. It was just enough for everyone to panic about the situation before everything went down. There was no definite way of telling who was left alive. Some neighbors yelled out to see who was still alive and if they were okay.
Some neighbors figured out how to share resources. They set up lines between the houses where they slid baskets back and forth. It could only last so long, but some of the more charismatic people made temporary plans that only benefit themselves. Some blindly followed them, believing that somehow they would share in the benefits of their actions. Others began to turn their back on these people, starting to form plans of their own.
Soon, people became desperate. They had no food or electricity. Tensions ran high because everyone was bored and on edge. Water was scarce. Some of the survivors resorted to sticking buckets out their windows and praying for some sort of rain. However, opening windows allowed it in. Overnight, half the household vanished without a trace. Survivors quickly learned to close their windows and doors at night.
Two weeks after everyone vanished, the survivors began to notice strange occurrences. Soon after night fell and the check-ins ended, locked doors began to rattle. The survivors heard voices from the other side of the doors. The voices of their loved ones. Some looked out their windows only to find no one there. A few survivors gave in to the emotional tidal wave brought forth by hearing missing loved ones again and opened their doors to them. No one was there. They ran out to find them and vanished.
Days after the sounds began at the doors, when the survivors learned to ignore them for their safety, the tapping began. The voices of loved ones muffled by the windows. Their faces dimly came into view. With no electricity, there was no light to show who was actually there. This broke more of the survivors and they ran out to reunite with their loved ones.
Very few survivors remained after a month. Supplies had been depleted and there was no way to acquire more. Rain was a rare phenomenon. The lack of activity and human interaction drove lone survivors insane. Rain came and some of them would run out and start to dance in the water, praising whatever higher beings they believed in for performing a miracle. They vanished as well.
The tapping, knocking, and doorknob rattling at night continued. The survivors learned to ignore all of it. Adapting to what was deemed the siren songs of the fallen became second-nature.
Halfway through the second month, the world fell silent. The remaining survivors climbed up to their rooftops at sunset. Nothing took them. They didn't vanish. As soon as the knocking at the door began at nightfall, everyone jumped. Bodies littered the world all over. They had been so twisted from a lack of food and water, that it would have been impossible to tell if they were human. That is, if anyone was left to identify the bodies.
As time progressed, the world became overgrown. Bacteria thrived and evolution began anew. The self-proclaimed second generation of Earthlings found evidence of the bodies 50 thousand years later. They tried to recreate what they believed they looked like, only to create creatures akin to aliens. Their eyes were sunken and black, with cheekbones barely visible. Their head bulged out after the temple, suggesting larger skulls and cranial cavities. Their ribs could open, theorized to be for the sake of concealment in certain situations. Their legs had multiple knees to them, allowing for greater flexibility.
They never found an intact human body.