What Is a Base Defense Game? A Plain Guide

If you have ever asked what is a base defense game?, here is the short answer. It is a game where you guard one fixed spot from enemies that keep coming. You lose when that spot falls, even if you are still alive. This guide explains the idea, how it relates to tower defense, and the parts that make it work. It uses Tank City Reboot as a worked example.

What is a base defense game? A simple definition

A base defense game has three parts. There is something you must protect. There are enemies that want to reach it. And there is you, with limited tools to stop them.

The base does not move. It cannot fight back on its own. If the enemies reach it, the run is over.

That last point is the test. In many action games, you lose when your character dies. In a base defense game, you can also lose while your character is fine, because you were in the wrong place when the base took its last hit.

Tank City Reboot is inspired by the 8-bit tank classics of the Family Computer. In the first game, the base is the CPU core at the bottom middle of the board. It sits inside its own firewall. Your antivirus tank guards it. Each stage sends 20 malware tanks. A single shot that hits the CPU core ends the game.

Left: the first game's board. Right: Zero Day's core integrity and the wave clear bonus.

How base defense relates to tower defense

The two ideas overlap, so it helps to pull them apart.

Tower defense

Tower defense is a subgenre of strategy games. The goal is to defend your territory or possessions by blocking attackers or stopping them from reaching the exits. You usually do this by placing defensive structures on or along their path. Those structures then block, slow, attack or destroy enemies on their own.

The key skill is planning. Where you place each defense, and which kind you choose, is the heart of the genre.

Base defense with a unit you drive

Some games keep the goal of guarding a spot, but hand you a unit to steer. You do the fighting yourself instead of placing towers. The base rule stays the same: if the base falls, you lose.

Tank City Reboot sits here. You drive the tank and fire the cannon. There are no towers to place. You win by thinking about where to be, and when.

Three parts of a base defense game

The base

The base should be easy to see. In the first game, the CPU core always sits at the bottom middle. You never have to search for it.

Walls

Walls buy you time. In the first game, the core sits inside its own firewall. A power-up called Firewall rebuild turns that wall to silicon for 15 seconds. That gives you a short window to leave the core and hunt.

Enemies with different goals

Not every enemy wants the same thing. In the first game, malware heads for the core, for your tank, or a random way. So you are always choosing. Do you chase the tank coming for you, or block the one heading for the core?

For more on how game enemies choose where to go, see our guide to how enemy AI works in video games.

Base health: core integrity in Zero Day

Tank City Zero Day is the second game on the site, at tankcityreboot.vlvd.net/zero-day. Here, the base does not fall in one shot. It has a health bar called core integrity.

• Core integrity starts at 3.
• A hit on the core costs 1 integrity.
• The run ends when integrity runs out, or when your last tank is gone.

You can make the core tougher. The RAID upgrade can be taken up to twice. Each time, it adds 1 to the most integrity the core can have and repairs it fully. That takes the core from 3 up to 5. If you want to know where the name comes from, read what RAID is in real computers.

Another upgrade, Hot patch, changes the walls. With it, every wave's arena starts with the core wall built as silicon. Our post on what integrity means in cybersecurity explains the real idea behind the core's health.

Worked example: why a whole core pays

In Zero Day, clearing a wave gives you a bonus. The sum is simple:

bonus = 250 x wave x integrity left / max integrity

Say you clear wave 4 and your core still has 3 of 3 integrity.

1. Start with 250.
2. Multiply by the wave number: 250 x 4 = 1000.
3. Multiply by integrity left over max: 3 / 3 is 1.
4. Your bonus is 1000.

Now say a shot got through and you have 2 of 3 left. The bonus becomes 250 x 4 x 2 / 3, which is about 667. One hit cost you about a third of the bonus. If you took RAID, a hit takes a smaller share, because the max is higher. Each time RAID is taken it also repairs the core fully.

The lesson is the same in any base defense game. The base is not just a fail line. How whole you keep it shapes your reward.

What makes a base defense game tense

The tension comes from two goals that pull against each other. You want to push out and clear enemies fast. But every second you are away from the base, it is open.

Zero Day adds a twist. Botnet drones hunt your tank, not the core. So they pull you away from the place you are meant to guard. If you chase them too far, something else can reach the core.

Bosses raise the stakes again. In Zero Day, the boss breaks any wall. Walls that held all wave will not stop it. Our guide to surviving boss waves in a tank game has tips for those moments.

Frequently asked questions

Is tower defense the same as base defense?

Not quite. Tower defense is a subgenre of strategy games where you place defenses along the enemy path. Base defense, as used here, also covers games where you drive a unit yourself to guard the base.

What happens if the base is hit in Tank City Reboot?

In the first game, a shot that hits the CPU core ends the game. In Zero Day, a core hit costs 1 integrity, and the run ends when integrity is gone.

How do you make the core tougher in Zero Day?

Take the RAID upgrade. It can be taken up to twice, and each time it adds 1 integrity and repairs the core fully.

Why guard the core if you still have tanks left?

Because the wave clear bonus grows with the integrity left. A whole core at the end of a wave pays the full bonus.

Get started

The best way to learn base defense is to guard something yourself. Start with the first game and keep the CPU core safe from all 20 malware tanks. Save Firewall rebuild for when the wall is thin. Then try Zero Day and see how long you can keep the core whole.

Play Tank City Reboot in your browser.