It's not a "some kind of One City Challenge thing". Netherlands, Portugal and Israel are city-states, and can't settle new cities until Renaissance. Netherlands got permanently removed in 5070, as without them Europe seems to function somewhat better (at least I don't see France and Germany die every game). Well, in 5070 AI is more picky both about alliances and about declaring wars. Should lessen the alliance pile-ups somewhat. And yeah, since it is a new feature, there is definitely some more balancing to be done. We're working on it. I actually don't know, but my guess would be that defensive use of alliances gets priority over offensive use. So in that case, A would come to C's aid in your first example. Well, AI doesn't really seem to know how to exploit basically anything. Once you peer under its hood, especially when it comes to diplomacy, most AI processes are pretty simplistic when it comes to planning and execution, and most are just probability-driven. Well, minors are supposed to be cannon fodder. But we'll be trying to introduce more diplomatic relation variables that will lead to less alliance sprawl, and more dynamic alliance system as a whole.