On a real bug, I've found that if a planet had culture tranmitters and had any colored lines radiating from it and you come in and sterilize the system completely, when you colonize it it immediately turns into the old race again. This happens even if you have conquered all system up to 2 jumps away. If the colored lines are still there after you clean that system out, you can't colonize it at all. You have to _completely_ wipe out the race to be able to colonize the planet with your race. This can be frustrating when there's a relic there you want to use there and the race has a colony hidden away in a corner of the galaxy and you can't get to them quickly.
Um, no. It takes forver and a day for the culture lines to die out but they do die out. It helps -- a lot -- if you both push the culture back with your
own culture centers, and wipe out "nearby" enemy culture centers, but even if for some reason you can it does, eventually, degrade.
In my last / current / way too bogged down game (culture again) I ended up wiping out an entire "string" (chain, maybe, since it wasn't just 2 exits to each system?) of enemy planets, and just sat my fleet on the node leading to them. Eventually -- and it took a while -- the culture lines died out and I could colonize. Even though the enemy was still beaming his culture in.
