Taking a page from the current political scene: have been talking about it alot at school,
1. Treaties might involve a corresponding input from the treatied partner, on economics (Are we lending credits to the Advent? And if so, do we get a say in their economic decisions? How much GDP is used for planet upgrades vs how many for ship production or orbital defense? This of course means expanding planet upgrades and what they do)
Right now, the amount of planetary upgrades are limited and fairly "unseen" all i see is numbers change, more logistics slots, more tactical slots, upgrade to population numbers. It would be very very nice to see planetary upgrades cover different and new things, such as agriculture or industrial production, or population growth, or different taxation rates for business or population, also structures that could be built "On Planet". Such as dedicating 20% to industrial structures and 50% to agricultural, 30% to population and see the world underneath my ships show huge swaths of amber wheat growing across 50% of the planet, 20% as black smoking industrial structures and 30% as urban/rural roadways and towns/cities. In other words we have control over the type of world we make, an industrial planet with imports of steel, or raw iron ore, coal, etc... from allied or treatied worlds/players (like crafts systems in other games where several items may be required to produce a given end item)
Or agricultural worlds, where i may sell off 70% to allied worlds (moved by ships no doubt, either mine or the allies ships) which produce a revenue stream (in addition to credits produced by population or taxation)
2. Governmental Interaction: meaning a Congress/Executive/Judicial structure, i propose a line of thinking, such as to expand taxes on businesses on planet to raise money to construct warships. However the Congress declines (congress in this case could be an ai) the third party in this case the Judicial, can be used to "break" the stalemate of only having two bodies me and the ai, with the third ai (Judiciary) sometimes aligning with me, and sometimes with the Congress. This could add an element of planetary interaction that doesnt exist now. And need not have a great deal of visual content added other than new screens.
In addition to taxes on businesses on planets, there could be perks for businesses that give the planet less money, but could be seen as percent growth of those businesses on planet. Tax breaks increase industrial area from 20% to 30%. Or cuts in industrial plants allow growth in population (which could be researchable to allow larger populations) or growth in agricultural (which option could be decided by the player) or AI in cases of NPC races.
3. Treaties could be "game lasting" and by that i mean that right now if i treaty with someone, anyone actually, i will have to fight them toward the end of the game. All treaties are only temporary, which makes me as a player, not really want to trust them, because while i'm aligned with them it gives them access to my worlds. And suddenly when they revolt, im fighting a force already in place on many of my worlds, not good. An alternative, would be to have some, not all treaties last the whole game, where when we win, all treatied races win together. Or if we lose the Advent-Tec Alliance falls to the Vasari together, know what i mean?
And just a final thought with regards to treatied NPC races, the real player should be allowed control over allied forces, or some control. To send them different places, in effect to use them as if they were our own forces, or to allocate them how they would, perhaps also on a sometimes yes, sometimes no basis.
Just some ideas,
-Teal