A good way to do that is lessening the idea that it's desirable to be alone and making playing as a nation more fun by having more activities done by the actual nation.
The way the nation works now:
>You are labelled as a group.
>You have certain bonuses.
>Your army can be supported by nation army.
My main idea about this is giving more perks to nations. Not just calculated bonuses but on how the game is played.
1) Permanent Nations
When you sign up you pick what country you want. No other option. No passwords too. Pick Nation A, B, C or D.
If you want a private password protected nation. You can probably pay a donation.
History has shown that when humans are forced together in groups for no reason they often go their separate ways.
Threats are always a uniting force. Which brings us to this.
2) Terrorist States
Make a terrorist nation. There will be 50 terrorists. The size of terrorists do not depend on the size of people. (Unless one person is too big, then terrorists will start targeting him, making people think twice about being on top.)
Say at day 4 terrorists range from $50m - $400k.
Day 8 - $100m - $20m.
Day 12 - $150m - $50m.
Etc.
People would have to keep up to not get hit and to fight back. (Don't make it too hard so people won't give up, just challenging.)
Will people just hit the terrorists instead of people? No.
Terrorists will be strong militarily and have less land. 40% less than normal.
Those that attack more will be hit more.
Those that have big land will be hit more.
Those that are always attacked or small will not be hit more.
(This is the great balancer)
3) Nation Attacks
Here's another thing to put people together. If you are a big state and your nation army sucks. You can be affected by nation attacks.
Can only be done during war and can only be done once every 12 hours. Nation Army assualt units vs Nation Army defence units.
No specialized attacks/ bombing runs/ air raids. Just plain old standard attack. Takes away 5% of the nation's land.
I also have some more ideas about the detailed implementation, but this is just a generalization. Opinions are well appreciated. We're a team.
Battles are fought with soldiers. Wars are fought with men.