I think that empires generated on the same planet are friendly by default, so that they don't insta-nuke each other.
I really hope so... I'm starting a multi-nation game soon.
I pulled wikipedia data on all countries with manned space flight capability and they're my major nations. Minor nations are any country with a space program and any kind of launch capability at all.
Everyone else is going into population pools separated by continent
So we'll have me playing the US, 3 other empires capable of space flight, 5 minor powers with TN tech but no space capabilities and then one population pool for each continent of everyone else on earth with no access to any of the new tech at all.
The non-TN populations will have their low-tech ground forces and massive populations but nothing else, pretty much just there to be conquered. Minor powers will have some up-to-date ground forces but no ability to go off-planet. I can trade with them or conquer them or whatever.
I'm hoping it won't immediately blow up in my face
USA, China, Russia and the UK all have manned space flight capability and so would be in a position to exploit the TN materials and technology and actually make ships so I'm starting each with a small shipyard and some tech. If I'm really lucky, they won't immediately murder each other.
I'm setting their industrial and economic settings based on real world data. For example china has a Per Capita of $8382 while the US is $48386, so if we use the USA as 100% of normal manufacturing and economy. China will have 17%, Russia is 34%, UK is 75%.
I'm doing that so that the sheer population doesn't blast China into the lead, and it should be fairly balanced and accurate to real world data.