What I would imagine is cool new units:
apart from classical infantry , (outdated) cavalry and artillery and armoured units (tanks), various ships and airforces, there also ought to be civilian units.
On one side policemen, elite commandos and guards, on the other (in)visible units such as terrorist cells and gangs/criminals. These unit types will be at first invisible - but to increase their influence the gangs will need to demand "protection" money and also vendetta warfare against rival mafias will occur. Similarly terrorists will carry out attacks.Any of these actions will increase the influence of these groups, but also their visibility, thus making it easier for policemen to track them down.
Also unarmed units will appear such protesters (at a demo) , migrants and settlers.
list of playable factions:
1.Sovereign states - goals similar to standard paradox games. (Special feature: de iure borders. This mechanic is similar to CK2. To legitimize your expansion the UN Security council members need to approve any border changes)
In this category are also unrecognized states such as Abkhazia or Kosovo)
2.Entities - highly autonomus subnational entities such as Swiss cantons or Rep. SRPSKA and FBiH.Also any "republics" of Russia
3.States -The constituent areas of federations such as USA or Germany.
4.Regions - parts of decentralized states (Russia, France)
5.Provinces- parts of unitary states . (E.g.Slovakia)
6.Territories-dependent areas, AO of Russia.
All of these will have four letter tags
Religious institutions (Churches) will have their goal to get as many faithful as possible. They will have borders of cannonical territories, and it will be them who can place missionaries.
Criminals will try to accumulate as many money and influence as possible while not being caught.
Terrorists will.. well you know.
NGOs and Corporations should be present in the game but only AI I guess.They will try to influence governments or accumulate money respectively.
Also new unit types: militia (recruited in times of need by subnational entities), insurgents and guerrillas/partisans (the last are invisible- they may hide and avoid battle).
Ethnic groups and religions should be portrayed to 5% accuracy.Also the game is to depart from large "provinces" to "districts" - with the size of Rhodos, Greece or slightly smaller than Luxembourg. Also apart from this ideology will be also present. (Communist, Socialist, Centrist, Conservative, Nationalist, liberal, Fascist,"Religious" , Authoritarian , Anarchist,...)
(My home Slovakia be divided into roughly 24 districts)
Also rebel types :
1.Social
2.Separatist
3.Ideological
4.Religious
also a new indicator: frustration. The level of frustration is higher if corruption is high, if stability is low and if mafia or terrorism is visible/has influence. Frustration means not only higher unrest but also more people in terrorism and criminals.
also maybe some political parties (Democrats, Republicans, Labour. .) should be playable.