Yes the initial colony tile is key to controlling the planet and the planet does indeed fall into rebellion as soon as the initial colony tile goes into anarchy. Basicly the initial colony tile always counts as a loyal tile ie it is never unhappy, but can go into unrest as a result of sorrounding anarchy tiles. The instant the initial colony goes into unrest, a revolution occurs. What happens to the planet depends on it's origins and the active galactic movements. Basicly, galactic movements are multi-racial confederacies, devoted to an ideology. Galciv I had galactic movements but Galciv II should have even more.
All galactic movements are activated by random events and persist until the death event occurs and the movement fizzles out. They represent ideologies that are current at the moment in the galaxy, they include wierd and obscure cults, fanatical groups such as the fundies and revolutionary or reactionary political dogmas. The I leugue is technically a galactic movement, but is always active from the games start to it's end. It's sort of the defualt which all planets that fall to revolts become, unless they fit the criteria of an active movement.
However if the planet was originally colonised by another race than the current ruler of the planet (this can include galactic movements) there is a very high chance that it will defect to that race upon falling to revolution. If that race no longer exists then it is recreated. The recreated civilization can be a major or a minor, if it is minor it regains it's seat on the U.P. council.
If a planet rebels then all ships that are in orbit of that planet defect to it's new owners (it is assumed they were boarded and captured). In addition ships that were built on that planet, this includes colony ships and transports will defect to the new owners aswell. This is to give these new civilizations a fighting chance against their former owners. Understandibly this also means that key shipyards that fall to rebels are potentially very dangerous, so it's important that you mantain such worlds loyalty.
Descriptions of galactic movements I would like to see and the criteria for rebellious planets joining it.
I leugue
The I leugue is a loose coalition of technicly sovereign worlds that exist under their own law, that have banded together for defensive and trading reasons. They believe in the right of all planets to govern themselves free from the interference of others.
Criteria- none
Fundermentalists
The fundermantalists are fanaticly devoted to the principles of justice and righteousness and to the sometimes forcible redemtion of all races, peoples and regimes that have turned to the path of evil. They seek to achieve the highest levels of moral enlightenment, justice and harmony throughout the universe and have little tolorance towards those who oppose their agenda.
Criteria- Evil or Nuetral civilization.
Dread Pact
The Dread Pact are the evil equivilant of the fundermentalists, devoted to all that is evil. They glory in fear, torture, cruelty and strength and seek galactic domination by any means. They aim to show the universe the awesome glory of the Dark side and destroy any who oppose them.
Criteria- Good or Neutral civilization.
The twilight pact
The third way are devoted to neutrality, balance and harmony. They disdain all extremes, veiwing both good and evil as equally dangerous, striving to walk the thin line between both extremes. They aim to unify the universe and all ways and peoples into one harmonious whole.
Criteria- Civilizations of a "Pure" moral aligment, that is pure good or pure evil.