City Defense: frequently asked questions

Questions and answers

What is City Defense?

A free tower defense game in the browser, played on a real 3D map of a city. You build towers on the roofs of real buildings, enemies walk real streets, and the map is built on the fly from OpenStreetMap data.

Is City Defense free?

Yes. It is free to play in the browser, with no download and no sign-up.

Do I need to install anything?

No. The game runs at citydefense.app. All you need is an up-to-date browser that supports WebGL 2.

Does City Defense work on mobile?

It runs in mobile browsers too, in high graphics quality even on a phone. If it stutters on a slower phone, it lowers sharpness and shadows by itself and offers low quality between waves. Phones get their own controls: the game status on top, buttons at the bottom under your thumb, and towers placed as a see-through preview that you confirm with ✓ – the money is only spent after that. You can also add the game to your home screen as an app.

How do I rotate and tilt the map on a computer?

Drag the map with the right mouse button held down, or click the map and use Shift + arrow keys. The scroll wheel zooms, and the arrow keys alone pan the map. Clicking the compass at the top right turns north back up and returns to the top-down view. More in How to play.

What language is the game in?

English and Czech. On your first visit the game picks the language from your browser (Czech or Slovak gives Czech, anything else English); you can switch at any time with the CS / EN switch on the start screen and in the ☰ menu. The missions other players share stay in the language their author wrote them in.

Which city is in the game?

The built-in mission is náměstí Svobody in Brno, Czech Republic (10 waves). You can create more missions in the editor anywhere in the world where OpenStreetMap has streets and buildings mapped.

Can I play on a map of my own city?

Yes. On the start screen, click “Create your own mission”, find your place, and the game proposes a defended area and enemy spawn points. See the guide Tower defense in your own city.

How do I send a mission to a friend?

In the editor or in the “My missions” list, click “Share” and send the link. The link carries the whole mission – the recipient can play it or edit their own copy. Nothing is stored on a server.

Does the game track me? Does it use cookies?

No. City Defense has no accounts and no cookies. We measure visits and game progress without cookies, only as aggregate numbers and never the text of your missions. Details and how to opt out: Privacy and analytics.

Where are my missions saved?

In your browser's storage, in the “My missions” list. The game has no accounts. If you clear your browser data, the missions are gone – a shared link works as a backup.

Where do the map and buildings come from?

From OpenStreetMap, the free map of the world built by volunteers. The game reads vector tiles in the OpenMapTiles schema served by OpenFreeMap. Map data © OpenStreetMap contributors, licensed under the ODbL. Details: Map data and credits.

Why is a building in the game taller or shorter than in real life?

The height comes from OpenStreetMap: the building's height (height) if it is mapped, otherwise the number of floors (building:levels) × 3.66 m, and 5 m if both are missing. The game deliberately uses no other sources, so that it works the same way in every country. You can fix it directly in OpenStreetMap – see Building heights in OpenStreetMap.

How many waves are there?

That depends on the mission. Brno has 10 waves; in the editor you can set anything from 1 to 50.

What do the visual themes change?

Only how enemies, towers and effects look (monsters, robots, mechs, zombies, skeletons, soldiers). The rules and difficulty stay the same.