Defending your colony is what this game is all about. Doing it effectively is what makes up the challenge. You need to make sure you understand how the enemy works. In turn, you need to know all of the defensive capabilities that are available to you so that you can fight off the enemy. It is not that hard to get your head around it all but it does require you to be on your A game the entire time to prevent any slip ups.
Zombies always take the shortest path
This is a key piece of information and is about all you really need to know about the zombies. They will take the shortest path to your command center. It doesn’t matter if there are walls and structures in the way, they will always take the shortest path. With this in mind, it allows you to cut corners in your defense and sort of make traps for the infected to fall into.
If you build a huge wall across a large open area, chances are the zombies will target a corner. They will hug the wall of a cliff or natural structure as this is the fastest way to the command center. You can keep this in mind and use it to your advantage. Design your defenses like a funnel. All of the zombies flush into the funnel and fill the area up. All of your towers will be in range to attack and your tithanos can then use his explosive attacks to hit a huge number of zombies. An explosion does damage in a circle. If zombies are in a row, it will only hit a section of the row. If they are bunched up together in a box, an explosion will have a 100% hit for the entire splash radius.
Fortify Choke Points
The scouting process is there to expose the game map for you. With the map exposed you should be able to pause and easily see all of the choke points on the map. Fortifying these points is fairly easy to do since you will require a smaller amount of resources to get it done.
Build double walls in sets of two
The game will only allow you to build a wall that is two layers thick. To be protected against the spitter enemies, you will need to have 4 layers between the spitter and your towers. Since your towers can shoot 5 layers and snipers can see for a huge distance, building 2 double walls or a double double wall will allow you to attack the enemies without taking damage yourself.
Build scratching posts
I found this to be a funny tactic but an incredibly effective one in buying you lots of time. Say you have a horde of zombies on the way from the east. They are going to attack your defenses on the east side. Which of the eastern walls do you add additional fortifications to if you have multiple eastern walls and limited resources? By the time you know, it will be too late to construct anything new. This is where scratching posts come into play.
If zombies are running down a straight path and they encounter a single pole from a wall. Even if this does not block their way, they will destroy it before they progress. In other words, they stop at the wall to scratch it before moving on. With enough of these randomly scattered around, it will buy you some time to construct new towers and move some soldiers around the map to further fortify the location they are about to attack.
Walls cost nothing to maintain and are cheap to build. The cost of doing this is incredibly low considering the payoff that you get from it.
Build defenses in layers as you expand
At the start, you will scout out the area and identify the choke points. Once you have the resources to do so, you will build walls and towers to protect these areas. You know in the future that you will expand beyond these walls. Do not let this be an excuse to build a “it will do for now” kind of defense. Build every fortification as if you expect it to be attacked.
When you expand beyond this defense later on, move the soldiers, but keep the walls and towers. Repeat the exact same process every time you expand. When it is close to the final wave of the game, you will find that you have lots of incremental defenses. Layers and layers of defense. If your highly fortified outer wall is breached. Pause the game and send the solders back to the next line of defense.
You can do this with the confidence of knowing that this wall was fortified and well built and can hold off the horde just as well as any other wall.
If you put all of your eggs into the outer wall basket and it falls, those crappy wooden walls and a single ballista tower you built on day 20 isn’t going to do a damn thing if the outer walls with all of the latest tech couldn’t hold it.
Zombies breaching the wall is going to happen. If you build your defense in layers and treat each layer like it is the first and last line of defense, you will be prepared for when the worst happens.
As you expand, there is no need to keep soldiers inside the towers. You can shut anything down that isn’t being used, just do not demolish it. When the time comes and you need these again, your troops from the front line can fall back and man these towers to form a second line of defense that was just as good as the first.
It doesn’t matter how much of your colony is destroyed. So long as there is a last defensive line that holds and the command center survives, you will win the game.
Place snipers into towers
Snipers have great range and when put into towers they can see an incredible distance. To top this off, they do a huge amount of damage. Fill the troop towers with snipers and set them to target the most powerful enemies first. They can one shot kill almost everything. With enough snipers you should be able to pick off most, if not all of the high level enemies before they even reach your walls. By the time they get to the walls, the rest of the defensive structures will only have basic zombies to deal with which should be far less trouble.
Ballista Towers are your best friend
The standard ballista tower without any upgrades does a damn good job at taking care of zombies. Make sure to build these to cover all of your defensive lines. They will be far more effective at crowd control than your sniper towers or soldiers. Toward the end of the game, you can start upgrading them to more powerful towers when the only thing you have left to do is prepare for the hordes.
Thanatos will destroy crowds
Like most infantry, Thanatos does not do well at close range. At a distance however, his explosive attacks can decimate large hordes of zombies in a couple of shots. You should aim to have one of these at every wall. They move incredibly slow which makes them fairly useless for patrols. By the time they arrive to the scene of the action, it will be too late.
Having more than one Thanatos at a wall is good, but not important that you should take one away from combat in one location and move to another. When there are two of them, the blast radius can often overlap. As in they both shoot the same location on the map. The first bomb explodes, destroying 90% of the zombies in the area. The second shot then might kill the remaining 10%. Not as effective. Especially if you took him away from a less intense battle where he could have killed 50% of the zombies in a shot. So place more than one at a wall but not at the cost of reducing the defense of another location.
Only use Titans if you have excess resources
Yes, Titans are the most powerful unit in the game and will destroy just about everything. They are like portable executor towers. The thing is, towers are a hell of a lot cheaper and you can built lots of them very easily. If you have a crazy amount of excess resources then you can build all of the Titans you want. Just remember that they consume oil as an ongoing resource and cost a lot to build.