First, wow; I am constantly impressed by what you are trying to do with this game.
Second, despite that, I would like to suggest a few change
Before you read anything please take a look at the at the attached jpg file; it's a map with the nodes named for easy reference (since I forgot to include a key, dashed lines are continent dividers, arrows are connections while red dots are nodes while blue dots are hubs, even in South America where I, for some reason, named them differently :/
(Also, f*** photobucket and its insistence on reducing my file sizes to 60kb)
Anyway, back onto topic
First, capturing nodes. Your current plan, I believe, encourages stat padding rather than war, so as to allow alliances to throw more score onto their nodes. In addition to that it means that a small, well coordinated alliance cannot take control of nodes because they cannot throw enough points at it, even if the alliance they face has 90% of its membership only checking in every ten days.
Instead, I would propose that they can be captured through war, and indeed make the entire war system based around these nodes and hubs. This can, I believe, be done through implementing a system of 'war goals'; an alliance can, at any time, declare an IG war on another alliance, and then it can add a war goal to capture a connected node; for instance, if alliance X controlled the Canadian Node and alliance Y controlled the Greenlandic Node alliance X could declare war on alliance Y and then add the war goal of capturing the Greenlandic Node.
Wars would last until the engaged alliances agree to end them, while war goals would last for either seven days or until the 'war score' is equal to or greater than one; if the war lasts seven days then it ends in status quo ante bellum, while if the 'war score' passes 1 then the attacking alliance gains control of the node and the the defending alliance has their nations redeployed to the continental hub (I'll go over what that could mean later). Once a node has been captured it new war goals cannot be declared on it for 100 hours (so as to allow defending nations to be deployed - once again, more on that later).
War score is calculated by the following equation:
(# of defending cities occupied)/(# of defending cities not occupied))(If (# of defending cities) = 0 then the attacking alliance automatically wins.
(More on what occupied means later)
An alliance would defend the node it owns and attack from them by deploying nations to the node; to encourage forward planning deployment wouldn't be instantaneous and instead would take three days; in addition to that once a redeployment is started it cannot be changed until the nation has arrived at its destination (you better watch out who you put in charge of your nation movement; a turncoat could suddenly order all your nations redeployed and leave you without defenceless)
Nations can only be deployed to nodes that their alliance controls and that are on the same continent that they are on (though they can attack over continental boundaries). Nations cannot, however, be redeployed from nodes that are currently war goals (so as to prevent heavily occupied nations being withdrawn to pull the war score down)
Hubs act slightly differently; Hubs can be contested by any alliance that controls 10% or more of the total score within the hub. Contesting a hub means that that alliance can declare war goals on nodes neighboring the hub; score is simply taken from the nation score that we have now. If you contest a hub you are able to attack from it to the neighboring nodes; if you do not contest a hub you cannot.
Now, onto what this means for wars on the national scale.
First, there would be no size restrictions; any nation can attack any nation, assuming their alliances are at war, though they may only use ground troops if they are in neighboring nodes or hubs (other attacks, such as air attacks, could be launched from anywhere to anywhere). This will of course need some balancing, but I don't believe that it will need much due to the occupation system; I would suggest a slight modification to the barracks would do it; using the following formula to determine the maximum number of barracks a nation can own.
30 + (# of cities) * 5With a maximum of 10 barracks in each city; and change their effects from
This would mean that a small (small by a couple of months time standard) nation with five cities could own 50 barracks, allowing them to maintain 50,000 soldiers while a nation with ten cities could only own 80 barracks, allowing them 80,000 soldiers; since under this proposal each city would need to be defended individually the smaller nation would have, in a sense, an advantage, given that they can deploy 10,000 troops to defend each city while the larger nation could only deploy 8,000.
Now is probably the time to explain occupation; a city would be occupied if the number of successful attacks less the number of failed attacks reaches 10 attacks (whether this little section will work will depend on how attack mechanics are implemented; it may need to be rethought depending on how they work). The last nation to successfully attack the city occupies it and can deploy troops to defend it as they would any other city that they owned but aside from that it does nothing and has no effect; neither the occupier nor the occupied can gain revenue or resources from its ownership nor does it increase the maximum number of barracks either nation can have.
Occupied cities can be liberated in three ways; the alliances fighting agree to peace, the nation is redeployed or the alliance successfully liberates it through force with the same mechanic under which it was occupied in the first place - if another alliance successfully occupies it then it is returned to the owner if the third alliance is not at war with the first, or occupied under the same mechanic if the third alliance is also at war with the first.
For this to work attacking and defending would need to work in a certain way; I see this as a nation could either deploy troops to an attacking pool or to individual cities as defenders; if deployed as defenders they cannot be used to attack and the reverse also would be true. Their stance could not be changed until either 24 hours after the nation last launched an attack or 24 hours after the stance was last changed, whichever is later; newly trained soldiers are automatically equally distributed as defenders in the nations cities (the exception to this is when occupying a city, after which 20% of the attacking troops are automatically assigned to defending that city)
This would mean nations could not use troops in attack and then immediately switch them to defence, meaning that nations will have to either try and balance attacking and defending or alliances will balance attacking and defending, using smaller nations with their higher troop density to hold a region while using larger nations with their higher troops numbers to seize enemy cities while allowing their own to be captured.
As for what the nodes will do I would suggest having something slightly different; rather than giving each hub an effect I would suggest taking the idea of alliance wonders and making it dependent on hubs; at each hub you own you can construct maybe two alliance wonders (if the node is captured then the wonders are captured with it, though I would suggest that if that means they have duplicate wonders then only one wonder gives them its bonus)
It would give alliances more freedom over which hubs they seize, allowing them to choose for strategic reasons, as well as meaning that you don't have to attempt to balance out the effects of each node, while still providing a massive incentive to controlling them.
While this does not quite slot in with your idea of ensuring cooperation between alliances I believe that it will still result in such cooperation; I doubt that an alliance working alone could defend more than a couple of nodes, meaning that they will have to cooperate or have to split their forces and lose all of their nodes to alliances that do.
As one last note, I'd suggest removing the cap on number of nodes that can be controlled; I believe that under what I have proposed above the number of nodes a single alliance could control would be limited by realpolitik; maybe an alliance could seize a chain of nodes, but as I said above I doubt a single alliance could hold more than two nodes that border non-controlled regions (and that would require them to the same size as their nearest two rivals put together, possibly larger depending on how many connections the node has)
I sincerely hope this is legible... I really couldn't be bothered proofreading it