World
What If Everyone Disappeared?
If humans vanished, what would the built and living world do over years?
This is not a horror story. It is a question about maintenance. Cities are machines that need people in the loop: fuel deliveries, cooling water, pumps in tunnels, coatings on steel. Remove the people and those loops open. Lights fail when generators starve. Underground railways, in places that need constant pumping, take on water in days. Vegetation is already waiting in cracks; a few growing seasons turn ornamental into woodland. Buildings last longer than gardens and shorter than stone. The slider is years ahead, from 1 to 1000, so the same page can talk about a silent subway and about a forested street grid without raising its voice. Pets, livestock and wildlife are part of ecology, not a gore reel.
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Your result
50 years
after people vanish
ruin woodland
- Clock
- 50 years
- Sketch of this moment
- ruin woodland
- Power plants without people
- long since tripped
- Pumped tunnels (simplified)
- flooded where pumps were required
- Street grid still readable?
- probably from above
What does that mean?
At 50 years, this sketch is: A woodland-and-ruin mix. Concrete spalls where water and rust reached the rebar. Glass is mostly gone from frames. Wildlife uses the structures as geology with corners. None of these lines is a prophecy for a named city. They are clocks — fuel, pumps, freeze–thaw, rust — that start when maintenance stops. The tone is ecology, not horror.
Timeline
Hours
Lights, then not
Grids fail as plants trip. Some hydro may linger. Domestic animals notice the missing routine first.
Days
Water goes where gravity said
Tunnels that depended on pumps take on water. Cold chains end. This is simplified hydrology, not a film sequence.
Years
Roots and roofs
Growing seasons beat pavement. Roofs admit rain. Wildlife uses the new edges.
Centuries
Steel, then stone
Reinforced concrete fails as steel rusts. Stone and some earthworks remain as geometry in a living landscape.
Compare scenarios
Hours and days are about power and water
Thermal plants trip without operators and without fuel logistics. Some hydroelectric and a few well-sited renewables could run until a fault. In a handful of hours to a couple of days, most grids go dark. Where tunnels sit below the water table, pumps are the only reason they are dry. Fail the pumps and the water line returns to where physics left it. That is hydrology, not drama. Food in fridges is a smaller, local version of the same idea: no power, no cold chain.
Years are about plants and roofs
Seeds do not wait for permission. Freeze–thaw, rain and roots open pavements. Wooden roofs fail first; then water gets into interiors; then interiors fail. Steel in concrete rusts where salt and rain reach it, on a clock of decades rather than weeks. Wildlife follows habitat, including the new habitat of an unmanaged park. This model is a sketch of those clocks, not a species list for your city, and not a claim that every subway on Earth floods on day three.
Centuries are about what was built of what
Stone, some bricks, and a few stainless or buried structures outlast the people who named them. Plastics fragment rather than vanish. Dams fail when spillways clog or when nobody lowers a reservoir for a storm. Atmospheric chemistry would notice the missing emissions: some pollutants drop fast; carbon dioxide is a longer tail. The slider at 50 years is a half-forested street with sagging roofs. At 500 it is ruins in woodland. None of this requires inventing monsters.
How we calculated this
The years-ahead control picks a paragraph from a qualitative succession timeline (hours, days, years, centuries) used in environmental science and in studies of abandoned places. Numbers that do appear — a year you chose, a century count — are clocks, not simulated biomass. Subway flooding is described as a simplified pump-failure story, not as a map. No body horror, no population model, no climate GCM beyond a mention of missing emissions.
Go further
A curated rabbit hole from this question. Each link is a real experiment, not a random suggestion.
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