What is a fog of war map?

A fog of war map is a map that starts completely hidden and uncovers only where you have actually been. The idea comes from strategy games. On a phone, your GPS trail does the uncovering, so the map becomes a record of the ground you have covered on foot.

Where the idea comes from

In strategy games, "fog of war" is the black shroud over the parts of the map your units have not reached. You start with a small lit circle and everything else is dark. Move a unit and the dark peels back around it. The term is older than video games (it comes from military theory, the idea that a commander cannot see the whole battlefield) but the black-map-that-opens-as-you-walk version is what most people picture.

A real-life fog of war map takes that mechanic and points it at the world you already live in. Instead of a fantasy continent, it is the actual street grid of your actual city. Instead of moving a unit with a mouse, you walk.

How it works on a phone

The mechanic is simple, and it is roughly the same in every app that does this:

• The whole world map is covered in fog by default. Not just your neighbourhood. Everywhere.
• Your phone records your location as you move.
• Wherever you go, a small circle of fog is cleared around you, usually somewhere in the range of a street's width.
• The cleared area is saved. It does not fill back in.

Walk to the shop and back and you get one thin line. Walk a different route home and you get two. Do that for a year and you get a shape: your part of the city, drawn by your legs rather than by a cartographer.

Most apps count anything you do at ground level, so walking, running and riding all clear fog. Driving usually works too, though a lot of people turn it off, because clearing a motorway at 70mph feels like cheating and it flattens the map fast.

What "permanently revealed" means

This is the part that makes the category worth anything. In a game, fog often comes back once your unit leaves. In a real-life fog of war map it should not. A street you walked in March is still lit in November, and still lit next year.

That permanence is what turns the map from a live tracker into a record. It is not showing you where you are. It is showing you the accumulated total of everywhere you have ever been, in one image, and that image only ever grows. Nothing you do can un-walk a street.

It is worth checking this before you commit to an app, along with what happens if you change phones. A map that cannot survive a device swap is not really permanent.

What it actually feels like after a few months

Week one is disappointing. You clear a few lines and the screen is still overwhelmingly black. That is normal, and it is the point. The scale of what you have not seen is the first thing the map tells you.

Around month two the shape starts to read. You can see your commute as a hard bright artery, your regular loop as a ring, and a dense scribble around wherever you live. You also start to see the holes: the block behind the supermarket, the park you always walk past instead of through, the four streets between two places you visit constantly that you have somehow never connected.

By month six it has quietly changed how you move. Not dramatically. You just take the other street home sometimes, because it is dark and it is right there and it costs you ninety seconds. Filling in a hole you have looked at for weeks is a genuinely satisfying thing to do on a Tuesday evening.

Why people bother

Two reasons, mostly.

A record. Step counts vanish. Photos are of moments, not of ground. A fog map is the only artefact most people will ever have of a life spent outdoors, and it accumulates without any effort: no logging, no journalling, no discipline. You walk, it saves. Years later you can look at a city and see exactly which parts of it you knew.

A nudge. It is a light, non-nagging reason to go the long way. There is no streak to break, no coach, no notification telling you off. There is just a dark patch on a map that you could remove by walking through it. That turns out to be enough for a lot of people, and it works on travel too. Two days in a new city with a fog map produces a very different two days.

If you want to see what a finished-ish version of this looks like, the cities hub has walkable cities broken down by area, and a map of everywhere you have walked covers the record side in more detail.

What to look for when choosing an app

The apps in this category look similar in screenshots and differ a lot in daily use. Four things decide whether you will still be using one in a year.

Background tracking

If the app only records while it is open on screen, you will not use it. The whole value comes from forgetting about it. Check that it keeps clearing fog with the app closed and the phone in your pocket.

Whether you can import history

Starting from a black screen is honest but slow. If you have Google Timeline history or GPX files from a running watch, an app that can import them gives you years of map on day one. Most people find that this is the difference between a toy and a record.

Subscription or not

Some apps in this space charge monthly. Ask yourself whether a map of your own walking, stored on your own phone, is something you want to rent. A subscription also means the map is hostage: stop paying, lose the thing.

Where the data goes

This is a complete history of your movements. It is one of the most sensitive files you will ever generate. Check whether the app requires an account, whether it syncs your location to a server, whether it runs ads or analytics, and whether you can export your own data and leave.

The category, and where FOG sits in it

Fog of World started this on phones in 2012 and is still the reference point. There are several apps now, including Stomped, Walksy and Fogbreaker, and they are all doing a version of the same good idea. If you already use one and it works, there is no urgent reason to move.

FOG is ours. Its case is on the four points above:

• Background exploring. It keeps revealing with the app closed and the screen off.
• History import. Google Timeline exports and GPX files, so years of past walks appear immediately. See importing Google Timeline.
• One purchase, no subscription. Free to explore. A single USD $5.99 purchase unlocks unlimited ranks, every character and history import. There is no subscription and never will be.
• The map never leaves your phone. No account, no sign-up, no cloud, no analytics, no ads, no tracking. You can export your data whenever you want.

On top of the fog itself there is a collection layer (241 countries, 3,390 regions and 7,342 named places, collected only by physically standing in them), ranks that climb with the area you have covered (Wanderer, Scout, Pathfinder, Explorer, Voyager) and a city percent, so for any city you have walked the app tells you how much of it you have lit up. It works for walking, running and riding, anywhere on Earth.

Head-to-head detail: FOG vs Fog of World, FOG vs Stomped, FOG vs Walksy and FOG vs Fogbreaker. Android: Google Play.

Questions people actually ask

Start with a dark map.

FOG is free to explore. No account, no subscription, and your map never leaves your phone.

free to explore · one purchase unlocks everything · never a subscription