I know at least in civ 4, you had to train the spies and devote resources to espionage activities, but in civ 5, it seems that there is no reason not to participate in the spy game. All the spies are free, and their operations cost nothing. This is unique in Civ 5, think about everything else: If you dont want to deal with the city states, you dont have to, and you can save yourself a lot of gold/work If you dont want to found a religion you dont have to, and you save yourself a lot of buildings If you dont want to build wonders you dont have to, and you get a lot of hammers to devote to other things. but if you dont want to have spies youre an idiot because theyre free and you dont get anything for not using them. Dont get me wrong, i like the current espionage system (it could do with some more options etc) but i think there should be a trade off.