I really miss these two back, I feel there's not enough things to do in Civ V currently. Still, espionage and religion aren't perfect in Civ IV, but I've been thinking how I would like to see them in Civ V. Espionage: There would be maybe like counter-intelligence, that would prevent other nations' esp. activity and it would collect data from other nations, and by an espionage slider I could invest gold into it. Maybe a too strict secret police would cause unhappiness? There would be also an "import" version of this, where I could make missions into city-states and other civs. But instead of moving the spy around myself I think it should be more about choosing a city-state or nation and what missions I would wan't to do there. I'm thinking about how CIA and KGB were converting small banana republics in the sixties and planting puppet rulers etc. so espionage would bring more interacting to city-states, which need more versatily anyway. Religion: I think a Civ IV system with the Apostolic votes and spreading are pretty nice, but maybe after middle ages religion should lose much of it's power. On the other hand, there are still holy wars going on I guess, but whatever suits game mechanics..