In my most recent game, I tried the zen-like method of dominating. It's discussed in another thread, but in short, once you get a small lead in tech, trade it to all the other civs in exchange for gold...preferrably lump sums. The effect is that you gain a ton of money, your neighbors all have equal tech for a while (until the late game, where some of them will undoubtedly fall behind several techs), while the other civs are hamstrung in terms of research because they give all their cash to you.
This worked wonderfully, until two things happened. Well, the same thing happened, twice. I had just agreed to give the Greeks Physics in exchange for 99 gold and 99 gold/turn. That would have been a huge boon at that point in the game, since I would be able to go 100% research and still bank about 2-300 gold a turn. Two turns later, the Greeks declare war on me, despite being POLITE toward me, and not even demanding anything first! Nothing major happened in the war...peace talks resumed shortly thereafter...but the trade agreement was severed, thus costing me nearly 1800 gold in the middle ages.
Later, after a larger trade with Germany, Bismarck pulled the same crap. No demands, no animosity, just out of the blue they decalre ware to spare themselves the cost of a tech.
At this point in the game, I've milked several techs for big money, and only those two occurrences slowed things down. It's not a widespread problem, but it does need to be addressed. As to how...that's a bit tricky, considering the implications of war. After peace resumes, will they be able to assume the payments?
If not...well, what then? Of course, there should be extreme political repercussions of backing out of a deal. I'd like to see other options, but it would probably too big of a pain to incorporate. Namely, if they can't pay up, maybe the bulk amount could be paid over a longer number of turns. Maybe the AI would be forced to sell off city imps to cover the cost. Or, most severe, the AI could be forced to surrender a city. Of course, all of these would apply to the player, as well, should he get sly with the AI.
