The results of treaties and diplomatic declarations should be primarily concrete effects. For instance at core an alliance doesn't mean that subjectively two empires are "friends", but concretely, that they can enter each other's territory without being shot down. This is a list of such diplomatic effects as i think may be useful. I expect many of them to be combined together as multiple effect of the same diplomatic status, and others to be judged unnecessary.
- For simplicity the effects are writing in first person. Some of these would only be available with their reverse.
- "Positive", "Neutral", & "Negative" refer the the way the recipient would view the effect.
- I'm not here including "trade" treaties where a player exchanges a tech, resources, planets etc for something else.
- I will share all the info my spies gather
- I will share the info my spies gather on our mutual enemies
- I will share all my current and new technology
- I will share my "vision" of the galaxy
- I will declare war on anyone who declares war on you
- I will allow your ship supply routes to run through my systems
- I will allow your planetary supply routes to run through my systems
- I will supply any of your ships if you cannot
- I will supply your non-military ships if you cannot
- I will repair any of your ships at my shipyards
- I will repair your non-military ships at my shipyards
- I will allow all your ships to enter my systems
- I will allow your non-military ships to enter my systems
- I will provide X% of my monetary income to you every year as tribute
- I will permanently adopt your foreign policy (Vassal)
- I will turn my military over to you, and hereafter rely on your empire to provide security. (Protectorate)
- I will only attack you if your ships enter my systems
- I will only attack you if your military ships enter my systems
- I will not allow your ship supply routes to run through my systems
- I will not allow your planetary supply routes to run through my systems
- I will attack any ships that leave your borders (limited war)
- I will fight to regain planet(s) X (limited war)
- I will fight to liberate species X (limited war)
- I will aggressively wage war against your ships and colonies.