In Endless Space Spying was... non existent, well it was there kinda, but it was never really a thing. But I had a few ideas on the subject...



In Endless Space all of the Science points that your planets produce go into a stack and then go whatever is in your research queue. the same is true for science gained from trade, all that science goes into the stack and then onto whatever your researching



So what if when you make contact with another player and if you establish trade or whatever. There is a chance that the other faction has researched things you haven't. Now instead of having all that science you just gained from trade go to the stack of science that is being used in your research queue, have A percentage of that gained science go directly into the techs that faction has researched and you have not.



Further this can play into espionage, like you could park a small fleet of ships who carry a special module that would allow them to leech directly from your neighbors. Also it could lead to a faction that sucks at generating science but excels at stealing it from their neighbors.



Now this sort of gain would likely only matter in the late game however you could make technology more interesting. Just as a thought what if each technology, particularly ship technology, had four "innovations" that go with it.



For Example: Players start with a Tier 0 Kinetic Weapons



But then they unlock Tier 1 Kinetic Weapons but in addition to that unlock they earn 1 innovation for that category of ship items. And they could choose between

Composite Construction: Reduces the tonnage of the weapon module by 10%

Improved Rifling : increasing Accuracy of weapon module by 10%

Depleted Munitions: increase damage dealt by weapon module by 10%

Barrel Cooling: increase number of shots by weapons module



Now each of those are good on their own. but during normal play you only unlock one, but with the technology leech from trade and spying you can gain another player's innovation.

But how would the state between factions influence spying technology gain? War and Cold War should increase espionage, as they do IRL, but peace would lead to more technological exchange, which would have a similar effect. And also, major innovations relatively quickyl get adapted by everyone else, without espionage, mostly because they're...well innovations.



What I think espionage should really also influence are politics and military. In Space, your Military is centralized in ships which makes sabotage easier than with a ground force. And IRL, a big part of cold war espionage on the soviet side was support of ideologically close political parties, in the third world, and, in many first world countries, terrorist groups, so maybe you could have stuff like that...your spies working the eco ideology could decrease enemy industry by doing eco-terrorism, while military spies could organize a group bombing your fleets, like in the event that is already in the game which decreases ship health(Which btw really sucks to get when you were just assaulting an enemy fleet).