I’d love to see some proto-state civs as something different.
All of the below were a significant thorn in the side of empires, all used irregular forces, all were famous for plundering and all had an impact on history. These plundering, highly independent ‘civs’
West Indie Sea Rovers (encompassing the interconnected Buccaneering Era, Pirate Rounds and Golden Era of Piracy). Home City: Nassau, Bahamas
Operating from pirate bases in Tortuga and Port Royal calling themselves 'The Brethren of the Coast, the Buccaneers had the organisation to field 1000s of English, French and Dutch Freebooters in sieges and sackings of fortified Carribean towns. When the Buccaneering Era ended the Buccaneers either settled down or became ‘true’ Pirates, leading to the Pirate Rounds (pillaging the Red Sea and Indian Ocean, using Madagascar as a Pirate base) and the Pirate Republic on Nassau (called ‘The Flying Gang’). The Sea Rovers have ability to ‘revolt’ early like Mexico, although it is called ‘The Pirate Round’. Making your civ go on the Round instead of aging up changes your Home City to Saint Mary (Madagascar) and allows you to ship powerful Madagascan Pirate Haven units such as Roundsmen (tough veteran pirates), various Malagasy tribe units, Rice Paddy wagons, etc. You can revert back to your original Home City to age up (this can be done any age from the Commerce Age). In the Industrial Age the Sea Rovers can also choose to ‘revolt’ (called ‘Royal Pardon) to whichever Euro nation governor they may have installed in the Governor’s Mansion, turning your civ’ into a nation’s Privateer base, with the Home City being London, France, Seville or Amsterdam and giving you a basic shipment card set plus access to all the respective civ’s buildings/units (a ‘light’ version of the real civ).
Zaporozhian Sich Home City: The Sich
The Cossacks fought (and allied) the Polish, Russians, Crimean Khanate (a Ottoman Protectorate) and the Ottoman Empire themselves and field excellent ranged infantry (Serdiuks) and light/fast cavalry (Sich Cossacks) as well as Chaika boats and Tabor wagons (can be deployed as garrisoned with gunpowder infantry as mobile fortifactions). Contary to the general view on Cossacks, their military are mainly infantry-based. As a nod to AoK and the hardy Cossacks, their Peasants (villagers) can be armed as Cossack Miltia when the Town Center bell is rang. Cossack Houses come with small farms alongside them.
Barbary Corsairs (Fleshed-out from the Revolution/Scenario civs). Home City: Algiers
The Barbary Corsairs/States are the longest-lasting of these plundering civs and despite being under Ottoman sovereignity, were very much operating autonomously. Units include the already available Barbary Corsairs, Marksmen and Corsair Captains though aging up allows you to pick one of the Barbary States for additional support/cards.
Shared mechanics:
Commanders
The explorer unit for these rebellious ‘states’ are flintlock pistol & sword-wielding Commanders. Buccaneer (and later, Pirate) Commanders for the Sea Rovers, Corsair Commander for the Barbary States and Hetman for the Cossacks. Can do all the usual explorer jobs as well as having a unique aura that allows nearby troops to Plunder. They can use shipped cards and unique techs to bolster the repertoire of cool-down abilities (such as a temporary health-boosting War-Cry and stealth-enabling Ambush)
Captains
Cossack, Buccaneer/Pirate and Corsair Captains are are ‘semi-hero’ units. They can be killed, lack the upgradable abilities of the Commander and you can only have a limited amount however they have a mini-Plunder aura and can also increase rate of fire.
Boarding Action
Garrisoning Commanders and Captains in any military naval vessel adds (and takes away, upon ungarrisoning them) the Boarding Action special ability. Basically old-school AoE Monk-style, this action slowly converts at close-range any military vessels to your civ. It takes fairly long time so your single Piragua/Dhow/Chaika with a Captain in is unlikely to convert a Frigate, however if you have some cheap ships to absorb the damage and a few captains in other ships trying to board, you’ll be far more successful.
Plundering
Either as a new resources (Plunder!) or as another source of gold, Plunder is aquired through attacking buildings and ships via sieging units as well as ‘mining’ it through special means such as a long cooldown ability to ‘deploy’ a shipwreck (fishable, water) or salvage camp (mining, land) a fair distance from any of your buildings (gives Gold to enemy/allies, so you want to get to it before they do). Plunder is used to pay for the most expensive/powerful units, send to your home city (reverse shipments!) to add bonuses to future shipments (for example add a few military units to the next shipments, regardless of shipment) or to speed them up.
Multiple Taverns/Kahvehane (Coffee House)
Taverns and for the Barbary States, Coffee Houses have a large (and upgradable) build limit as these are the main barracks-style building as well as coin generator,
Governor’s Mansion (Sea Rovers), Palace (Corsairs) and Rada (Cossacks)
This unique building allows Coin/Plunder to be spent on National alliances which means extras. units, techs and wagons. Barbary states are the most limited with mainly Ottoman support (though arguably the strongest), followed by the Cossacks who can choose to invite Crimean Khanate, Russian Polish or Unaligned (Sich) diplomats for support. The Sea Rovers get to invite a pirate-friendly English, Dutch, French, Spanish or Unaligned (Pirate!) Governor. Like the Cossack Rada’s diplomatic options, you can only choose one governorship at a time although you can kick out the current one and invite another in for a cost. National governors enable a few Basilica-style shipments related to a nation. For example, the West Indie Sea Rovers may invite French support which allows them to exchange Coin for a small shipment of Coureur de Bois or in the case of all of the Euro choices, a Garrison Wagon (to build a stripped-down barracks capable of training ‘Miltia Pikemen’, ‘Miltia Musketeers’ and ‘Militia Light Cav’ - essentially re-skinned, slightly weaker counterparts to the Euro units, to make up the short-fall of unit types), with the downside being reduced Plundering. The Unaligned choice would allow full a Plundering rate, more special abilities and a number of unique Piractial units. Cossacks may decide to welcome the Crimean Khanate to allow Tartar horsemen trainable from the stables. The Barbary Corsairs are very limited as they are ‘stuck’ with Ottoman, although Mameluks and Bombards are very welcome.
Aging-up
These civs all feature a simlar Aging up mechanism which is mixture of existing ones. Essentially you pay the amount to Age Up and then are presented with a few Pirate Havens (West Indie Sea Rovers), Sichs (Cossack military centers) or Barbary Strongholds (Barbary Corsairs). Each of these come with their own roster of cards (using the special card row that Federal civs use), which are all exclusive to that selected Pirate Haven/Sich - representing your colony/settlement’s newly added location on its network. This entire row of new cards are only useable during that Age as when you Age Up next, your rebelious state/organisation needs to choose another to focus on. For example the Barbary Corsairs may choose Barbary State Tunis as the next Pirate Haven which means they have access to unique shipments such as Galiot boats and european naval techs though when they next age up and pick Algiers, they lose the previous Pirate Haven’s exclusive row though gain a completely new one with new units and techs.
The downside is that your ‘real’ card sets are limited far lower in number. The other plus is that there will be ‘named Captains’ available within the special cards. For example, aging up with Brethren of the Coast - Port Royal for the West Indie Sea Rovers will (among the other unique cards to Port Royal) allow you to ship Captain Henry Morgan, his ship and a small mixture of units within (if no water shipment points, you receive cannon instead of the ship). The captain is the same as the normal ones (names are just flavor) except they allow you to go over your captain limit.