Diplo in Civ5 is always about knowing what the AI is thinking and exploiting it. You can use Diplomacy quite well, but if you piss of an AI civ to any extent they will go crazy and try to make unreasonable demands. There is also a code that will flag an AI civ as greedy, its the kind of civs that will come up to you asking for open borders and 5 of any strat resource and offering only open borders in return.
It can be used. The most fun if you are rich and there are 2 strong AI civs is to ally one of them, exploit the heck of the trades (Sell everything you have extra of) and then bribe the other in declaring war against your friend.
But its very poor indeed. Especially when you ramp up the difficulty level and, instead of playing smarter, they are simply given loads and loads of bonus resources...
Heck of a fun and addictive game though...
Can you spot all the wonders in this city?
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