Some ideas for new Civilisations to diversify old Civilisations like the Burgundians are alternative Franks and the Sicilians are alternative Italians.
Disclaimer: I think new Civilisations in Africa or North America have higher priority.
Also the Ideas are not complete. There can be additional Bonuses.
I also don’t specify every missing/available Technology.
Alamannia
Civilisation to represent Germanic tribes, the Southern Holy Roman Empire and Switzerland.
Architecture is Central European but could be Western European too.
Unique Unit
Reisläufer (alternatively Lanzknecht):
Heavy and slow infantry with attack bonus against cavalry. Cost more Gold than Food.
A lot of Condottiero where from southern Germany and especially Switzerland was famous for their Mercenaries called Reisläufer. Lanzknecht where the German copy of that concept.
Unique Technology
Castle Age all Pikeman transform into Reisläufer
Imperial Age Town Centres produce a small Gold trickle
Civilisation Bonuses
- Castles function as drop of building for all resources and can train Villagers
- +2 garrison for all Rams
- Spearman line +1/1 armour (Maybe Militia line too)
Team Bonus
Allies can train Elite Reisläufer in Imperial Age at the Castle that only costs Gold. 1/3 of the Gold cost is paid to the player playing Alamannia (the Gold is split in case multiple people play the civilisation)
Available Technologies
Fully upgraded Paladins and Champions but bad Archers and no Hussars.
Have Gunpowder units.
Gameplay
Infantry focused civilisation that has good Knights(no bonus but all upgrades).
The Castle bonus allows to build a Castle earlier in Castle Age because it also functions as a Town Centre (without being able to research it’s technologies). Perfect to be dropped next to valuable resources, making sure they can’t be raided.
The Ram garrison bonus makes them faster and stronger and helps the Infantry too by giving it cover from Archers.
The Spearman bonus helps them already in Feudal Age and compensate for bad early Eco and makes them more useful in Lategame.
Their Imperial Age Unique Technology gives them the dilemma having to choose between Castle and Town Centre for their econom.
Poland
They are very different from Russia and Slaves in the game are basically that. At the moment it’s better to represent them using Teutones.
Architecture Set is Central European not Eastern European.
Unique Unit
Pancerni Armoured Cavalry with Lance that is good against other Cavalry.
The bonus against Cavalry is not as strong as the one of Camel units.
Unique Technologies
Castle Age
Imperial Age +1/0 armour for all units (yes including Villagers, Monks and Trade Carts)
Civilisation Bonuses
- +1/0 Armour for all Cavalry
Team Bonus
Available Technologies
All Cavalry upgrades besides Paladin.
All Archer Upgrades besides Parthian Tactics.
No Plait Mail Armour (Infantry) at the Blacksmith.
Gameplay
Cavalry focus but has also surprisingly strong Archers that have all upgrades and even +1/0 armour.
The Pancerni are perfect addition for a cavalry Army that makes up for the leak of good Pikeman (missing Armour upgrade makes them very weak against Archers).
The Hussars have +2/0 armour making them useful in Lategame, the Cavaliers are also good because they have all upgrades and +2/0 armour.
Knights are strong in Castle Age thanks to +1/0 armour and Bloodlines being available.
Czechs
Could also be called Bohemians.
Architecture is also Central European.
Unique Unit
Hussitan Wagon Wagon that can garrison Archers and Hand Canons. Can switch between mobile and stationary (like Trebuchet). Garrisoned units can shoot when stationary.
Unqiue Technology
Castle Age Destroyed buildings spawn 1-5 pikeman (depending on the building House 1, Castle 5)
Imperial Age Stationed Hand Cannons shoot bullets (in case that is somehow possible) maybe let Towers always shoot bullets.
Civilisation Bonuses
- Stationed villagers boost the production speed of the building by 10% each up to 100% (10 villagers) making it twice as fast. Villagers can be stationed if Military buildings.
- Villagers +5/10/20 HP in Feudal/Castle/Imperial Age
Team Bonus
All military buildings (Barracks, Stables and Archery Range) can station +10 units.
Available Technologies
Most upgrades for Infantry.
Ok Cavalry, Archers ans siege.
Hand Canons have full upgrades.
Gameplay
Defensive civilisation that is very different from other defensive civilisations.
The Hussite Wagons allow for offensive defence and the units that are spawned but destroyed building make raids, especially with cavalry harder.
The bonus from stationed Villagers gives unique strategies, like stationing villagers sto age up faster. Only having 10% bonus per villager makes it not overpowered in early game because every villager is needed for resource collection. This bonus also helps defence again as villagers can be stationed in military buildings to hide from attackers and at the same time let those work faster.
Southern India
Southern India has a lot of different Civilisations so I didn’t choose one yet. Maybe Vijayanagara.
Architecture is Southern Asian.
Unique Unit
Tiger Claw (See AoE3) Fast Infantry functions like the Eagle Warrior (has the Eagle Warrior armour class) but they are cheaper, less armoured and have no attack boni against Monks and Cavalry. They are still excellent Archer killers.
Unique Technologies
Castle Age Camel Riders produce a little food and Battle Elephants Wood (Like AoE3 Home City Card).
Imperial Age
Civilisation Bonuses
- Villagers cost Wood (maybe 25/25 Food/Wood) (This one is extreme so maybe not)
- Market building and Trade Units cost 50% less wood.
- Farms cost 50 Gold but give infinite Food.
Team Bonus
Trees lasts 15% longer.
Available Technologies
Most Upgrades for Heavy Camel Rider and Elite Battle Elehpant but no Hussar and no Knight at all.
Most upgrades for Infantry and Archers.
Gunpowder Units are available.
Gameplay
They have a decent economy and and solid Infantry and Archers.
Their Unique Unit makes up for the leak of good Cavalry. Camels and Battle Elephants can also make up for that a bit but they are weaker than those of most other civilisations because of the leak of good boni for them. Camels and Elephants are indirectly cheaper as they produce a little resources.
Their Team Bonus is helpful in maps with little wood.
Southern China
China is a huge and diverse civilisation. Southern China is different from Northern China, why not show that. Maybe Song.
Architecture is East Asian.
Unique Unit
Fire Lance Archer that shoots small rockets. Deals AoE damage but low rate of fire. Good against other Archers, slow Infantry and Buildings.
Count as Gunpowder unit and don’t benefit from Ballistics.
Unique Technologies
Castle Age Volley Fire gives Crossbows +2 (maybe 3) attack bonus against Cavalry (and Camels/Elephants)
Imperial Age Pikeman cost half population
Civilisation Bonuses
- Villagers cost 40 (maybe 45) food
This bonus might be enough.
Team Bonus
- All military units train 5% faster.
Available Technologies
Most upgrades for Archers and Infantry (maybe no Halberdier).
Bad Cavalry. No Cavalier, no Hussar.
Battle Elephants but no Elite Battle Elephants.
Gameplay
The lower Villager cost helps in early game but is also very nice for booming.
The Fire Lances are a perfect addition to every army but are weak against cavalry when not defended because their low rate of fire and no Ballistics. The Attack bonus against Cavalry for Crossbows and the lower population cost for Pikeman can help with that though.
West Roman Empire
They outlasted outer civilisations in the game like the Huns so why not. They already appear in a lot of campaign missions.
Architecture is Mediterranean.
Unique Unit
Legionary Infantry that is good against other Infantry and has decent Piercing Armour (Maybe 2/4 Armour on Elite).
Unique Technology
Castle Age Legionary available in Barracks and can build them.
Imperial Age Towers cost 75 Stone and 50 Wood.
Civilisation Bonus
- Barracks, Stables and Archery Range cost 25% less.
- (Elite) Skirmishers have +1/2 Range in Castle/Imperial Age (But no Bracer available)
- (Heavy) Scorpion +4/6 melee damage (With the default 3 melee armour from the Blacksmith that’s only +3 Damage in Imperial)
Team Bonus
- All Buildings are constructed 10% faster
Available Technologies
Most University Technologies besides Keep and Arrow Slits.
Most Infantry and Cavalry Technologies including full upgrades Paladin without Bloodlines.
Archers are mediocre.
Most Siege units available.
No Gunpowder Units of course.
Gameplay
They have a very strong all round Infantry unit as Unique Unit that can withstand Arrow fire and is efficient at killing most Infantry (besides Jaguar Worriers and Samurai).
They can also build Barracks at the front to maintain production. They should be supported by Pikeman against Cavalry. Skirmishers with extra range are a good support against Archers but leak Bracer.
The good Siege Weapons are helpful. And the cheaper military buildings save wood.
Towers are bad (No Keep, Arrow Slits and Bracer) but very cheap thanks to the Unique Technology making it easy to cover a wider area.
Their Scorpions are especially dangerouse for other siege weapons because of their extra melee damage.
PS:
About Central European Architecture. I added 3 civilisations with that Architecture because I think the Goths, Vikings and Huns don’t fit in there. Especially the Huns, there is nothing Central European about them.