All units and buildings have a certain number of hit points. When a unit or building is attacked, it loses hit points based on the attacker's training and experience level, and based on the amount of armour it has. Units can also lose hit points through starvation.
Units die (and buildings are destroyed) if they completely run out of hit points. Damaged units can regain hit points by being healed in a hospital, buildings can regain hit points by being repaired.
The amount of damage done by an attacker is based on its basic damage, plus its experience level, minus the amount of armour the defender has. Although the principles are the same, different types of combateer attack in different ways:
You can get information about individual units and buildings by clicking on them. The graphs? and statistics? menus also give an overview of how your population is doing.
Some units (and some buildings) are armoured against enemy attack. Each point of armour deflects one point of damage done by an attacker, although warriors and defence towers will always deal one point of damage no matter how much armour you have.
Warriors start off with 10 points of armour, minus 10 points for each piece of fruit they ate in the last inn they went to. A warrior that took two pieces of fruit with his last meal will have -10 armour, meaning that he takes 10 extra points of damage for every blow he is dealt. Armour lost due to fruit doesn't accumulate, so if the warrior eats no fruit the next time he takes lunch, he will go back to having 10 points of armour.
Defence towers do a certain basic amount of damage based on the level they've been upgraded to. Level one towers do 30 points of basic damage, level two towers do 40 points, level three towers do 60 points.
Explorers' air damage is worth 8 basic points, as is their ground damage once they've learnt it.
A warrior's basic damage depends on its attack strength. Learning attack strength to level 1 gives it 8 basic points of damage. Learning it to level 2 gives 16 points, level 3 is gives 24 points, level 4 gives 32.
The more experience a unit has of combat, the stronger he gets. Units start off with no experience, and gain one experience point ("XP") for every point of damage they do to an enemy (after armour is taken into account). Eventually, they will get enough XP to go up to the next level of experience, which means that every blow they land in combat does another point of damage. As they go up a level, their new level is shown in yellow next to them for a moment.
For convenience, here is a list of experience levels - in practice, it's very rare to get above experience level 10.
Details of the experience system
The details of the experience system are given here, but if you're not interested in numbers, this section can be safely skipped.
The formula for working out the number of XP needed to advance from one level to the next is cl2 where l is the level you want to get to, and c is a constant based on your unit type (20 for warriors, 50 for explorers). Experience gained getting to one level doesn't count towards the experience you need to get to the next, so the total amount of experience you need to get to a particilar experience level n is the sum of cl2 from l=1 to l=n.
Getting into a fight
Explorers won't attack unless they fly directly into (or over) an enemy unit. Defence towers will attack any enemy unit or building that comes into its firing range. Warriors will attack any enemy they can see within an 8x8 square around them.
Putting it all together: an example
Note: This could be expanded and moved into the unit section later on.
A new warrior emerges from one swarm, a new explorer emerges from another. They each start with an experience level of 0 and 0 XP. They each deal 8 points of damage for every attack they do. They each take a moment to look around for things to do. The explorer sees nothing to do, so he begins to fly across the landscape to see what he can find. The warrior sees several barracks he could train in, and a war flag in the distance. He prefers the war flag, which he immediately heads toward.
Soon, the warrior finds himself in combat. He and three other warriors surround a market and start attacking it. Each blow he lands should do 8 points of damage, but the market deflects 2 points with its armour. After he hits the market four times, he has done 24 points of damage and gained 24 experience, so he gains an experience level. Now, each blow he lands does 9 points of damage, minus 2 because of armour. The warrior gets three more blows in before his team-mates destroy the market. As the warrior retires to a nearby inn for lunch, he has 1 experience level and is 25 points towards reaching level 2.
In the mean-time, the explorer happens upon an enemy explorer. The explorers fight, dealing each other 8 points of damage for every blow they land. Luckily, the enemy explorer had previously lost a hit point through a moment's starvation, so dies after being dealt 24 points in 3 blows. Like the warrior, the explorer has gained 24 experience, but because he needs 50 experience points to go up a level, he remains at level 0. After the fight, the explorer has only one remaining hit point, so makes his way straight to the nearest hospital.
The warrior finishes his lunch and takes an orange, which takes his armour level from 10 down to 0. He looks again for something to do. There are no war flags any longer, although there is a guard area nearby. Most of the teams barracks are full with other warriors now, but there's space in a level two barracks, which he immediately signs up for.
As the warrior enters the barracks, the explorer leaves the hospital. Still not hungry, he looks for something to do. There is an exploration flag on the other side of the map that needs more explorers, which he heads for. But he gets hungry before he can make it there, so turns round and heads for an inn. After lunching at the inn, he sees a level 3 school with an empty place, so goes there to train.
The warrior leaves the barracks with an attack speed of 3, so now he will attack three times as quickly as before. There are now two guard posts - one nearby and one in the distance. He heads to the nearby one. Soon, two enemy warriors pass near the guard post. He goes to attack them, and it turns out neither of them have any experience, skill, or armour. They are no match for him, and he gains two experience levels fighting with them before they flee. The warrior gives chase, but they have a much higher walking speed, so they manage to escape. The warrior heads to hospital then to an inn.
When the explorer leaves the inn, he heads back toward the exploration flag set there before. When he arrives, he finds a group of 7 warriors marching to attack his base. He begins attacking the warriors which are unable to fight back. The enemy warriors choose to keep marching despite this and arrive at the base with only half their health. The 4 friendly warriors now fully healed also join the fight. Despite superior numbers the enemy units are defeated due to the damage taken from the explorer.