Ok, I play Proportions game. My race is Rock Oxygen. AI is with bonuses and no pushovers. I am at war with 3 races. There are buffer systems and so far we had only minor skirmishes, no one lost any colony yet. One day EEE decides to colonize a nice Gas Giant in the buffer zone. Great ! I can find a use for CO2 breathers ! Now, in case somebody did't play Proportions - Population is very important, you can not simply catch few transports and then spread people according to atmospheres. No, you need a lot of population for each planet. I mass my ships, capture EEE planet and strip it of the inhabitants wich I transfer to one my planet. Well, it is not enough. I need more slaves ! So I develope a cunning plan - I give the planet back to EEE, wait untill it is repopulated and then come back. I send my fleet back and ask EEE to have the planet as a gift. They refuse (??) but few turns later send a fleet and recapture the planet. Splendid, everything goes according to the plan. Meantime I clean my CO2 planet from my people. The foundation of a new city outside the old Dome has been laid. Next month, the EEE fleet, apparently resupplied on the captured planet warp in, goes directly to CO2 planet and glass it !
Here I am - like before the devious operation "Slavehunt", not a single EEE slave alive and one planet less
Conclusions : 1) AI is smarter then me
2) EEE is run by Stalin. Traitors are enemy of the people and shall be eliminated. I guess next time I come for EEE they will rather kill themselves than go to my transports...