Fogbreaker
Ask anyone who has lived somewhere for a decade how well they know it and you will get some version of "like the back of my hand." Then ask them to point at a street ten minutes from their front door and say what is on it. The confidence usually survives about four streets.
The gap is not ignorance. It is that walking a city feels like covering it, and it is nothing like covering it. Your commute, the shops, the park, the two routes to the station: repeat those for ten years and the feeling of thoroughness is entirely earned, even though the map says you have touched a sliver.
So what is the real number? It turns out to depend enormously on what you decide to count, and the two obvious methods give answers that differ by a factor of ten.
Two ways to measure, two very different numbers
Street completion asks what fraction of the named streets inside a boundary you have set foot on. Walk the full length of Oak Street and Oak Street is done. This is the model behind every "walk every street" project, and it is the one CityStrides and the apps like it are built on. It flatters you, because a city has fewer streets than you think and a single long road can clear a lot of them at once.
Area coverage asks what fraction of the ground inside a boundary you have physically been near. Not the street as a line, but the land as a surface. This is much less flattering, because a street is thin and a city is wide, and the space between the streets never gets counted no matter how far you walk.
Neither is wrong. They answer different questions. Street completion measures whether you have visited everywhere; area coverage measures how much of the map you have actually seen. If you have ever wondered why two apps can give you wildly different scores for the same year of walking, this is why.
Why the area number starts so small
The arithmetic is worth doing once, because it explains the shape of everything that follows.
Walking reveals a corridor, not a line. Say the fog clears roughly 15 metres either side of you, so your path sweeps a strip about 30 metres wide. Walk 10 kilometres and you have swept:
10,000 m x 30 m = 300,000 m² = 0.3 km²
Now put that against a real city. A compact European city is around 100 km². A sprawling one runs to several hundred.
| You walk | Ground swept | Share of a 150 km² city |
|---|---|---|
| 10 km | 0.3 km² | 0.2% |
| 100 km | 3 km² | 2% |
| 1,000 km | 30 km² | 20% |
And those are ceilings, not results. They assume every kilometre is fresh ground. In practice you re-walk the same corridors constantly, so the same 1,000 km spread over a year of ordinary life might land nearer 5% than 20%. The overlap is not a flaw in the measurement. The overlap is the finding: it is the shape of a habit, drawn.
This is also why "I know this city" and "I have covered this city" are such different claims. Knowing it takes a handful of well-worn routes. Covering it takes deliberately going somewhere you have no reason to go.
How Fogbreaker calculates it
We shipped this in version 4.0.0 as a feature called Territories, and the method is the area one, computed honestly rather than estimated.
Every place you walk is matched against real administrative boundaries, five levels deep: country, region, district, city and neighbourhood. Each one gets its own entry with three numbers behind it, the total area of that boundary, the area you have uncovered inside it, and the percentage that gives. The boundaries come from the Overture Maps Foundation, so a neighbourhood is the actual neighbourhood, not a circle drawn around your GPS trace.
In the app it shows up in three places. The Map tab outlines the area you are standing in, in orange, with its name in the corner; pan around and you see the outline of whatever you pan to. The Home tab has a Your Area card for wherever you are right now. Tapping it opens the full list, where you start at countries and drill down through regions and cities to individual neighbourhoods.
Two things worth saying plainly. The percentage is land area, not streets, so it will read lower than a street-completion score and that is expected rather than a bug. And it is not a Pro feature. Territories is free, in full, for everyone. Pro changes the discover radius, the XP rate and the speed limit, and none of those are the scoreboard.
Small numbers are the point
The first reaction to seeing 0.4% next to a city you have lived in for eight years is usually a small insult. Give it a day and it turns into the opposite, because a number that low means almost everything is still unopened, and the part of your city you have not seen is within walking distance right now.
A percentage that started at 90% would have nowhere to go. One that starts near zero rewards every genuinely new street forever, which is the same reason the blank map in a strategy game pulls harder than a finished one. We wrote about that mechanic in more depth in fog of war for real life.
It also reframes what counts as a good walk. Under a step counter, a 5 km loop you have done two hundred times scores exactly the same as a 5 km loop through streets you have never entered. Under an area percentage, only one of them moves anything.
How to actually raise the number
Nothing exotic, and all of it is just the deliberate version of what you already do:
- Walk the parallel street. The single highest-yield habit. Your usual route almost always has an untouched street running alongside it, and taking it costs you nothing in time.
- Leave by a different door. Vary the first five minutes of a walk rather than the middle. The start of a route is the most habitual part of it and the cheapest to change.
- Go outward, not around. Loops re-cover ground by design. An out-and-back into unfamiliar territory sweeps more new area than a scenic circuit of the same length.
- Do the interior. Cutting through a residential block, a park path or a passage covers ground that main roads never reach, and those interiors are where the unswept area actually is.
- Pick the neighbourhood, not the distance. Instead of "I'll do 6 km," pick a neighbourhood sitting at 2% and go put a dent in it. It is a better organising principle than a step target, and you will walk further without noticing.
The honest answer
If you have never tracked it, your city is almost certainly in the low single digits, and your country is a rounding error. That is not a personal failing. It is arithmetic: a person on foot sweeps a 30-metre ribbon, and cities are enormous.
The useful part is not the number itself but what it does to the next walk. Once somewhere is measured, "I'll take the long way" stops being a whim and starts being a move.
Fogbreaker is free on iOS and Android, Territories included, and if you want the concept rather than the scoreboard, start with fog of war for real life. If what you actually want is to tick off every street by name rather than sweep area, we would genuinely point you at the street-completion apps first: that is a different goal, and they are built for it.
