This is from an old post I was sketching but never published and got down my list. I've reread it and seems nothing is off topic or outdated. Anyway, it is not a compilation of the previous discussions linked above in this thread (sorry). It is mostly in line with labgnome proposals, and makes no consideration on micromanagement issues (which now I am quite concerned).
I envision three general categories of influence projects depending on its function:
- Espionage: to get info from others or to avoid others getting info from you.
- Sabotage: to destroy assets or hinder production of your enemies.
- Propaganda: to incite revolts on enemy colonies or to repress them in own colonies, and for peaceful assimilation of natives or foreign colonies by improving the opinion they have on your empire.
For all sabotage and espionage operations there are chances of discovering who was conducting the operations. Only if, or more so if, stopped (countered) by the enemy.
And that would affect relations among the involved factions. Sabotage operations will also lower public opinion of the empire from the affected species, so no good for influence conquest of the affected planets/species and can be counterproductive for your own Empire if it also has the affected species (e.g. if you terrorise an enemy Abaddoni colony using mass destruction weapons, your own Abaddoni colonies could get lower happiness).
The influence projects I can think of:
- Investigation/Recognisance (espionage): report of planet facilities, armies and activities (beyond current detection capacities), and grants the vision from that planet as long as the project is online.
- Steal technologies (espionage): gets PP for a given tech you are researching that is owned by the enemy.
- Counter-espionage (espionage): makes harder to finish or even cancel enemy espionage/sabotage projects.
- Building destruction (sabotage).
- Ship/fleet destruction (sabotage).
- Assassination (sabotage): lowers influence production on that planet by killing influential figures.
- Terrorism (sabotage): lowers happiness, cheap and effective but can't be used to conquer the planet (it does not raise public opinion on you, and if countered it will greatly decrease that public opinion).
- Mass-destruction weapons (sabotage): lowers happiness and kills population without the need of orbital domination (can eradicate and revert the colony to outpost if intense enough), but it is harder to achieve than terrorism.
- Incite revolt (propaganda): lowers happiness, chances to destroy buildings, armies and/or population depending on how much the happiness approaches zero (intensity of the revolt) and the presence of order forces in the planet. If the owner can't counteract the enemy influence and the happiness reaches zero and stays there for long enough, chances for the planet to become independent increases. If that happens, it becomes a "native" planet.
- Imperial marketing (propaganda): slowest influence project that lowers the affiliation of the planet to its empire and substitutes it for affiliation to the influencing empire. "Affiliation" is a concept here, I don't know how the effect of this project could be implemented, but I assume the happiness meter alone can't do this. This could be a general project that works both inside and outside the empire, i.e. at the same time getting new planets for you and stopping others from influencing your planets.
- Incite desertion (propaganda): targets a fleet/ship and, if it succeeds, changes affiliation of that fleet.
As said before, I think all projects, when possible, should be empire-wide.
However, projects like "building/fleet destruction" seem clearly a targetted project, I mean, aimed at a single object (planet, fleet) instead of at anything under range. Because it could be OP or hard to balance if empire wide, and because the "size" and resistance of the target should be considered against your own influence power (so that bribing huge fleets with cutting-edge technology to join your ranks costs more than bribing a lonesome, outdated scout; same for getting for you a foreign planet, it should be harder to get a colony with huge population well within its supply lines and thriving in its Empire's trade, than a small, isolated and underdeveloped colony in the verge of the Empire).
Therefore, despite my reluctance, I think it is better to make those projects targetted, and make them cost enough so that having a few of these online depletes all your spare influence. As long as huge empires don't have increasingly available influence points, this could work charms.
So, I would make targetted projects all espionage (except counter-espionage, empire-wide), all sabotage projects, and the Incite Revolt/Desertion projects. That is, most of the projects in that list :s
But I would keep Imperial Marketing/Propaganda as an area-of-effect project (everything under range, including allies, so you could be getting planets from your allies, which could then start a war against you to combat your treacherous influence conquering). Or... have two versions of the "influence-conquering" projects, one empire-wide and one targetted (with smaller overall influence cost, but greater influence-per-planet-conquered cost).
BTW, diplomatic mission seems like something to stablish alliances between governments (empires), more than changing allegiances of a population. But dunno what could be a better name.