Government Types

Ordinary Crusader Kings 2 has a few government types:

• Feudal
• Iqta
• Nomad
• Merchant Republic
• Republic
• Theocracy
• Tribe

Obviously, these are inadequate for the full 5,000 years of entertaining gameplay. A few more a needed.

Hunter-Gatherer
The hunter-gatherer government type represents pre-agricultural humans who, as suggested, hunted and gathered. To properly simulate the hunter-gatherer experience, the only possible succession law will be gavelkind, and forming titles will be impossible. This will limit most hunter-gatherer "realms" to bob around one province, since it's not like sprawling hunter-gatherer empires are a thing.

Like nomads, hunter-gatherers will avoid holdings (being unable to construct any holding type) and will rely on an army raised with prestige or gold, with population and manpower. Unlike nomads, they won't blob over your lovely Eurasia with their bullshit horse armies.

Native Council
Native councils are the government that native Americans and Siberians have in EU4. I don't know much about them, but they'll probably be a mix between republics and tribes in terms of succession and gameplay.

Monarchy
Monarchies will represent despotic and absolute monarchies, rather than the precarious decentralised nobles of the feudal system.

Dictatorship
Dictatorships are the autocratic states of the modern era. I'm not sure how these will work either, but it will be sort of like republics except with less freedom somehow.

Other Changes
Republics will have patricians etc. to allow them to be playable. Theocracies will also be playable. 'Twill be good.