Good debate here. Some pondering:
- Some system of visible trade routes would be greatly benefitial for the game, for it would mean less doomstacks (tm) and more strategic positions / chokepoints
- Integrating trade routes with other game systems such as refugees, factions and global food seems like a good, logical step
- I don't think that an in-depth system of multiple consumer goods would be benefitial for the game, considering that 1) We already have a consumer good system in place that acts like a good balancer of production and tall / wide empires and 2) most of us wouldn't like to see the game devolve into a spreadsheet simulator either. A fine balance between depth and abstraction / playability would be the optimal choice, me thinks
- Considering that the game is already quite procedural by itself, to add another layer of procedural-ness might end up being counter productive, as there are lots of possible exploits and loops, considering how "galactic geography" works
With all of that taken into consideration, I think that this could be a good trade system for Stellaris:
- Every empire will be able to attract corporations. They operate in the same vein of political factions. They will demand certain actions for the player to meet (ej: Colonize 3 additional systems, secure a Zro supply, reach X popullation, research X technology, etc). Also, note how favouring one corporation will disminish the strenght of their competitors, and vice versa.
- Once a corporation gains enough strenght level, it will grant a trade route to your empire. State-controlled economies will allow you to pick and choose the trade route's destination, while free market economies will present significantly stronger trade routes, at the expense of their control. Trade routes will be visible on the map to every empire that has charted at least one of the systems where it has been stablished
- The more time a trade route is operating with no piracy, warfare nor interruptions, the more it will grow in size and thus, the more bonuses will provide for both your empire and your trading partners, and its corporate owner will grow stronger as a result, too
- The more trade routes a system has, the more powerful said trade routes will become, and more corporations will want to stablish trade routes with said system. So yes, strategic trade hubs will be a thing.
- There will be a maximum cap of trade routes that a system can sustain depending on its popullation. So trade routes will help "tall" empires, so to speak
- Note how the benefits of these trade routes will vary from one corporation to another, hence why the player will need to ponder which corporation should support. Every trade route will provide extra credits and inmigration to their empires, but certain corporations will provide additional happiness, military ships, science, unity, planetary bonuses, and so on. Ej: "Tyrell corporation: +5% to synthethic pop yields at both sides of the trade route per level" VS "Weiland Yutani: +10% to inmigration towards both sides of the trade route, 5% chances of obtaining xenomorph troops per level"
- Once they reach a certain strenght level, corporations will act as lobbies too, strenghtening or weakening certain empire factions. The more their trade routes grow, the more powerful their political clout will be and the more expensive will be to interfere with their internal affairs (ej: telling a corporation to stop trading with one of your rivals or to support one faction over another will cost you more influence if said corporation is extremely strong and well stablished).
- Some really powerful corporations (and their trade routes) could survive external conquest, even if war will of course weak them out. Conquering empires will decide then whetever to mantain their old foe's corporations or to disband them so they don't become subversive trojan horses
- Certain goverments can strenghten, weaken and manipulate corporations in order to do their bidding, either by giving them subsidies (paying a certain amount of credits per month), giving them political support (paying a certain amount of influence per month), by nationalizing them (gain direct control at the expense of heavily weakening them) or by adopting certain decrees or policies (giving rights to AIs will weaken Tyrell Corporation's strenght, while scientific grants will help them out)
So in short, a "commerce overview" screen would be something like this:
Tyrell corporation
Motto: "More human than human"
Strenght level: 7
Bonus: +5% synth output per trade route level level
Lobbying: Agains the Synthethic rights movement (-20% against their influence), in favour of the New World's Pioneers (+15% to their influence)
Active trade routes:
Earth - Alpha centauri: LV4 trade route. +5 credits, +20% to the synth output of Earth and Alpha Centauri
Earth - Cadia (controlled by the Tau empire): LV 8 trade route. +15 credits . +40% to the synth output of Earth and Cadia
Active policies affecting Tyrell Corporation:
Recieving moderate state subsidies: -15 credits per turn, -10% happiness in your empire, +2 corporate strenght levels, +1 Trade route levels