Not if you are allied to him.
I feel they come into play too late, require me to build a small wonder, and even then require me to build them in that one city...
There should be a spy-type unit from, say, middle-ages. Sun-Tzu speaks of spys...
Of course, his mission-options would be less than modern spy... Maybe tech stealing, beakers for research of a tech, spreading rumors and dissent, (angry citizens), few plaqued rats, (health), and of course keeping an eye on things in general.

I feel they come into play too late, require me to build a small wonder, and even then require me to build them in that one city...

There should be a spy-type unit from, say, middle-ages. Sun-Tzu speaks of spys...
Of course, his mission-options would be less than modern spy... Maybe tech stealing, beakers for research of a tech, spreading rumors and dissent, (angry citizens), few plaqued rats, (health), and of course keeping an eye on things in general.
Comment