The most important aspect of staging a strong defense is building walls and other defensive structures. A starting nation can build a basic stone wall, as well as a primitive cannon. As a nation develops, it can research advances that unlock the ability to build more sophisticated defenses that protect more effectively and deal more damage to attackers.
To build a wall or defense, click (or tap) on an empty square occupied by your nation and select Build… from the menu. The Build Menu will then appear, showing a list of all the defensive structures that are available to your nation given the advances you’ve researched. Below the picture of each defense, the various costs for building that defense are displayed: the amount of manpower it will take to build it, the amount of energy it will cost per hour to maintain it, and the amount of time it will take to construct it. You can also find out more information and stats about any defensive structure by clicking (or tapping) on its (i) info icon in the upper right corner of its picture.
Every kind of wall or defense you can build will add some amount of hit points to the square that it’s built in, making it more challenging for an attacker to capture. Many defenses have the ability to fight back against an attacking nation, as well. For example, the starting cannon will attack a nearby enemy square for 5 to 10 hit points of damage, when the nation that owns it is attacked within a radius of 2 squares from the cannon. More advanced weapons can be developed that deal greater damage, and that attack when triggered within a greater radius. Some defenses are triggered in different ways, some leave the land they attack uninhabitable for a period of time, and some are geared toward attacking enemy defensive structures or retaking captured Orbs and resources. A few defenses are capable of such devastating annihilation that enemies would do well to avoid triggering them at all.
Most defenses, after they’ve been triggered, have a brief cooldown period during which they cannot be triggered again. While a defense is cooling down an orange timer ring will appear over it on the map, indicating how long until the cooldown period is complete.
After you’ve built a particular kind of wall or defense by selecting it from the Build Menu, you can easily build more of the same kind. Say you’ve just built a Rocket Launcher by selecting it from the Build Menu. Now, if you click (or tap) on another empty square occupied by your nation, a new option will appear in the menu, “Build Rocket Launcher”. In this way, it’s simple to build many of the same kind of defense (this is especially useful for walls). And, if you’re using a device with a keyboard, you can build multiple of the same defense even more quickly by simply holding down the Ctrl key while clicking on squares that belong to your nation.