About › How to play

How to play City Defense

In City Defense you defend a spot in a real city against waves of enemies. Between waves you build towers on the roofs of real buildings – the taller the building, the longer the range. Enemies only walk real streets toward the defended area. Survive every wave of the mission to win; each enemy that gets through costs you a life.

Updated September 30, 2026

The goal in a nutshell

• You defend one spot in a real city – in the first mission, náměstí Svobody (Freedom Square) in Brno, Czech Republic.
• The game is played in waves. Between waves you build at your own pace, then start the next wave with a button or the space bar.
• Every enemy that reaches the defended area costs you a life (a boss costs five). Run out of lives and you lose.
• Survive all waves of the mission and you win. The Brno mission starts with $350 and 20 lives and has 10 waves.

You earn money for every enemy you kill. The game can run at 2× or 4× speed.

Towers go on the roofs of real buildings

To build a tower, click a roof (tap it on a phone): a see-through preview of the tower with its range appears, and you confirm it with ✓. Every building in the game is a real building from OpenStreetMap with its real height from the map data. A tower's range grows with the height of its building: the machine gun reaches 90 m plus 1.5 m for every meter of height, so on a 20-meter building it covers 120 m.

Direct-fire towers (machine gun, laser) need line of sight. For each tower the game works out which stretches of street it can actually see from its roof. While you place a tower, a preview shows the streets it covers, with enemy routes drawn thicker. While a tower is picked for building, the ranges of all your towers stand out more. Ballistic towers (grenade launcher, mortar, howitzer) fire over roofs along a real parabola – and can hit the facade of a building in the way.

The sight tag (an eye and a percentage, for example “👁 62%”) above the see-through preview of a machine gun or laser tells you how many meters of the enemy routes in range the tower can really see from this roof – buildings hide the rest. Below 35% it turns red, above 70% turquoise, in between it stays white. If no route runs through the range, the tag says “no route in range”. The grenade launcher, mortar and howitzer don't need line of sight, so for them the tag says “over the roofs”.

Upgrading towers

Between waves, each tower can be upgraded twice (levels 1–3). Each level adds 40% damage, cuts reload time by 15% and adds 15% range. Level 2 costs 70% of the tower's price, level 3 costs 120%. The tower panel shows the numbers before and after the upgrade.

Between waves, rings pulse around the towers you have built. A bold ring with an amber arrow means the tower can be upgraded right now – it isn't at the top level and you have the money for it. Click or tap it to open the upgrade panel. After the very first tower you build, the game reminds you of this once.

Moving and selling towers

Until the next wave starts, a tower built since the last wave can be moved for free (keeping its level) or refunded in full – building cost and upgrades. Once a wave starts, it can only be sold for half in the following breaks between waves, just like when it falls with its building; you confirm the sale with a second tap or click. The buttons are next to the selected tower between waves; during a wave towers cannot be moved or sold.

Enemies only walk real streets

Enemies come out of spawn points on the edge of the play area and take the shortest route through the real street network to the gates of the defended area. A gate is any point where a street or footpath crosses the edge of the defended area. Enemies slightly prefer roads, but they will happily use a sidewalk, a pedestrian zone or a passage through a building. Each wave, enemies get 25% tougher.

The mission decides which types appear; the Brno mission has all of them. When enemies attack a building your tower stands on, the tower defends itself and targets them first. Otherwise it aims at the enemy closest to the goal.

Buildings have hit points and can collapse

Every building has hit points based on its volume (150 to 1,600) and loses floors as it takes damage. Blasts from ballistic towers, the howitzer, airstrikes, dynamite and enemy attacks all hurt buildings. A collapsed building buries the street around it in rubble – 8 to 18 m, depending on its height.

• Walkers and Armored enemies cross rubble three times slower, or walk around it – the game works out which is faster.
• If a building with your tower collapses, the tower is lost and you get back half of what you put into it.
• Buildings inside the defended area and outside the play area cannot be damaged.

Dynamite and airstrikes

Dynamite (2 charges per mission) brings down a building of your choice between waves. A preview shows which stretches of street the rubble will bury. You can't use it inside the defended area or on a building with a tower.

An airstrike costs $150 and works during a wave too. The bomb lands 2 s after you click: buildings within 15 m take 400 damage, enemies within 20 m take 200. It then recharges for 20 s of wave time. The preview tells you in advance how many buildings the bomb will bring down and how many stretches of street it will bury.

Bosses

A boss joins the wave once the spawn points have released half of it; several bosses in one wave arrive one after another – two after a third and two thirds of the wave, three after each quarter. Bosses are 2.5× the size of a normal enemy and cost you five lives if they get through.

• Crusher walks over rubble without stopping. It deals 30 damage per second to every building within 10 m and brings down a building its path runs through (a passage – the pink “Passage through a building!” marker in the top-down view) in one go.
• Besieger stops and shells buildings with towers from up to 150 m.
• Summoner releases two Runners every 6 s.
• Shieldbearer halves the damage taken by every enemy within 20 m.

The boss bars at the top show their health. Click or tap a bar and the camera flies to the boss and follows it for up to 10 s; if you move the map, following stops. With several bosses, another click on the same bar moves on to the next boss. In the Brno mission the Crusher arrives in wave 5 and the Besieger in wave 10.

Themes and city style

On the start screen you pick a theme under “Enemies”: Monsters, Robots, Robots – Mechs, Zombies, Skeletons or Soldiers. A theme only changes how enemies, towers and effects look – the rules stay the same. Under “City” you choose the city style (Stylized, or Realistic with photo textures) and next to it the quality (Low or High). Low quality is meant for slower computers and phones.

Controls

• Map: drag to pan, scroll to zoom, right mouse button to rotate and tilt. After you click the map, the arrow keys pan it too and Shift + arrows rotate and tilt it. The compass at the top right rotates the map when you drag it and, when you click it, turns north back up and returns to the top-down view. During the first mission a short help card shows the controls; you can open it again in the ☰ menu.
• Building: pick a tower in the bar at the bottom and click a roof – a see-through preview of the tower with its range appears. Fine-tune it with the arrows around it or the ← ↑ → ↓ keys and build it with ✓ or Enter; the money is only spent then. Shift + click builds right away (as does the “Build without confirming” option in the ☰ menu at the top right). Click an existing tower to upgrade it (and, between waves, to move or sell it – moving uses the same preview).
• Space starts a wave, M (or “Map” at the top right) switches to the top-down view with the enemy routes, X makes buildings see-through (so you can spot enemies and streets behind them), Esc removes the tower preview, a second Esc cancels the selection.
• On a phone: the game status is on top, the Towers, Dynamite, Airstrike and Wave buttons at the bottom (on the right in landscape). After picking a tower, tap a roof – a see-through preview of the tower with its range appears. Nudge it with the arrows around it and build it with ✓; the money is only spent then. Dynamite and airstrikes are confirmed with ✓ or a second tap on the same spot. Tapping an existing tower opens upgrade, move and sell. A long press on a building shows its state.