this is exactly the same as Alliance except the time limit but alliances shift and change so thats covered as well.

I like this idea, it's like the concept that was used in Romance of the Three Kingdoms.  So if any one power becomes too great, the weak can join together to fight them off.

And this is ENTIRELY different from Alliances.  It would be a goal of all the weaker forces joining together to fight a strong or more overwhelming force.  Thus it can also act like a balancer in the game to help prevent the super kingdom landslide, where if someone becomes powerful they just steamroll all the weaker forces.

Overall this would be a great thing to work into this game because it can give players a challenge from all sides (if they form a coalition against you, you may lose large amounts of trade).  And you may be forces to fight on multiple sides instead of picking a single country to pick off one at a time.

I think it's a great idea, and it could easily prevent someone from being too powerful, but any country could rise from the ashes of the coalition to become more powerful than the others.

This would be a great logical choice that could be enabled/disabled in the game, and could tie in the the United Planets!  Everyone votes for a coalition due to this one person being too powerful and evil, so they all join in to fight the same foe...  (or go the route of the Romance of the Three Kingdoms, where one person initiates it and it then queries other teams or people one by one if they want to join in (making it have variable strengths by the number of people))

Just my ten cents.

I think what he is trying to offer is a way to make things challenging once you get powerful, if these so called Coalitions should be directed against the powerful, there is a major difference between alliance and coalition. The strong can be part of alliances, but coalitions are against the strong and pointed towards survival of anything that threatens the lives of billions. Perhaps if the requirements are meet when starting a coalition against the invading civilization, others who fear the powerful will likely strike the undefended sectors forcing the attacker to pull back and defend. The AI has been a focus of this series, and I believe that whatever fancy algorithms they have in their arsenal will be enough to determine how the strong AI reacts to the coalition.

You might find that the strong AI/player may be burning a hole in his wallet up keeping a fleet to successfully defend his giant empire making a coalition a intelligent choice to make when you are pitted against an empire of that scale against so many lesser and insignificant fleets ripping apart anything like weak space stations to undefended planets.

I believe in constructive answers, you must give proof that this idea is bad before you trash talk it. (links, websites, pictures, etc.)