http://wiki.spaceo.net/index.php/Guide:Galaxy:Planets#Planetary_InvasionAdded some more info to make it clear what happens:
Planetary Invasion:
Attacker forces: Marines on the invading ships battle ground forces. Marines get 1 Hitpoint & 1 Attack Point / man. This is further modified by the planetary combat skill. If you have a 15% skill, you get 1.15 HP / AP / marine.
Ground Forces: The colonists are also the defense force, they use the equipment on the planet (planetary defense structures / armory / etc) to defend the planet.
Colonists get 2 Hitpoints & 1 Attack Point / man. This is further modified by the planetary combat skill, planet type, planetary structures. You'll see the whole combat bonus if you scan the planet. For example if the combat bonus on the planet is 50%, then the colonists get 2*1.5 = 3 HP & 1.5 AP
Planetary shields will halve the marines attack power and produce less colonists casualties. Each planetary shield adds 5% to absorb, up to the 80% max.
Attacker invade options:
-> Raid (receive 20% of the minerals / credits on the surface, planet enters rebellion and can not be attacked anymore for 24 hours)
-> Conquer (only available if researched technology supports adding another planet to the max planet numbers, grants access to all resources on the planet, 50% of everything is destroyed by rebels, gives ownership of planet to attacker.)
-> If the planet owner has a space station in orbit, planet can only be Raided, not Conquered until space station has been destroyed.
To win Raid -> Planet casualties have to be 50% or more of planet colonists / workers, while attacker casualties <50% (20% of planet resources are deposited on the attacker mothership, 10% are destroyed.)
To win Conquer -> Planet casualties have to be 80% or more of planet colonists / workers, while attacker casualties <80% (Remaining colonists are enslaved and join the attacker, remaining on the planet surface. All loot is deposited on the attacker mothership.) (50% of planetary structures are destroyed)
Invasion combat special events:
- Surprise attack for marines in planetary combat, will increase marine wave attack by 1-25%
- Entrench for colonists will give the colonists attack bonus for that wave 10-30%, and 25-50% bonus to hitpoints to that wave and the next ones.
Note: If there are many workers on the planet and less resources to justify the marine expense in battle, the planet won't pose much of a target profit wise from raiding unless it is in a strategic position. Conquering would always be an option as opposed to the cost of building / upgrading a planet, provided the technology to support an additional planet has been researched.
- An enemy can not deploy a station or any fleets in a system that has a foreign planet.
- Can not deposit credits on planet, just load
- Can not take colonists off the planet once populated
Invasion attack details:
- Attacker fleets land on surface and deploy troops one by one: Each attacking fleet will deploy a marine wave, max of 10 attacking waves (if 10 fleets with enough marines).
- The total number of marines + colonists at one time on the planet defending / attacking wave can not exceed 105% of the planet capacity.
- Each new attacker wave can have increasingly more numbers on enemies due to the loss of colonists on the previous wave.
- Once an attacking wave has been deployed, fighting will commence. Defenders will fight the attackers until.
- Once the defenders lose the required % of their default numbers, or the enemy waves have ended, victory conditions will be determined, surrender or repelled.
