You made good suggestions Skadilesu.
Make Huskarl regional unit unit : yes, originally there were a saxon unit.
Make Cataphract a regional : yes I agree, I find nice picture of armenian Cataphract
Give Palitonon to the romans, huns, goths and new civilizations, a nice skin of the trebuchet and historically accurate. Trebuchet were not is use in Europe in this time they still use torsion engine.
Vandals
Yes there is a consensus about the vandal civilization but I think there will be an cavalry and naval civilization. After their conquest by the byzantine empires, the byzantines use them as a cavalry unit. Of course they need the camel. Also they make big used a demolition ship, they need a bonus to their demolition ship, maybe the former +50% HP of the chinese ?
Alans
Good design but I think they don’t need to have the camel because they never use them in Europe and later they merged with the vandals. Steppe lancer of course. Not having an elite upgrade for the UU is weird, they need an hidden upgrade like the fereter for the armenian warrior monk.
The Alans can also replace the mongols who play the Scythian int Attila campaign.
Saxons
I think than giving infantry upgrade one age earlier is too much like the armenian bonus maybe only for the huskarl line.
Or maybe make an unique huskarl UU like the camel scout of the Gurjaras. A feudal age huskarl who automatically upgrade to normal huskarl in the castle age. Maybe the huskarl line can have a feudal age version for all the civilizations ? Maybe 3 stage for the huskarl : earlier huskarl in feudal, huskarl in castle and elite in imperial ? Also having a feudal age stage huskarl is good because historically this unit was most in use during the feudal age and the earlier castle age
I suggest : huskarl in feudal and free upgrade for the huskarl line for the saxon.
Byzantines
I think than giving Legionary is not good for the byzantine because they don’t use them after the 7 th century.
Your concept of varangian guard is good, because there were an praetorian guard unit who protect the emperor in the city of Constantinople, so the bonus next to defensive building is good. But in AoE4 they can also build transport ship, so I suggest than in AoE2 they can repair ships (viking who a come from Scandinavia with their longship) in additon of the armor improvement next to buildings.
For the flamerthrower unit maybe but we can also make a regional of Greek fire grenadier infantry for the Byzantine and Saracen. This type of grenade were more in use than any flamethrower infantry.
Suebi
The Suebi follow the vandals In Iberia, they carved a big kingdom, look at the Wikipedia article : Kingdom of the Suebi. In 446 they control most of Iberia peninsula. A campaign in the reign of king Rechila will be good.
Campaign : the story of the Suebi people from Germany to their kingdom in Iberic peninsula. In their journey they invade Gaul with the Vandal and the Alans, after this they invade Iberic peninsula with the two former people and stay in Galicia after than the Vandals and the Alain were beaten and leave to Africa. The campaign finish with a fight against the Wisigoth in Spain.
For the UU I suggest an Angon thrower : Angon was a barber javelin. When stick in a shield she cannot be removed and lower the ranged armor. Also if he hit a body the barbed javelin cannot be removed, you death from bleeding. The angon thrower is a skrmisher or a ranged melee unit with a charged attack : every time he hit with is charged attack he lower the ranged armor of his opponent by 1 (like an obuch) and only the ranged armor. Also the charged attack make more damage (maybe a progressive damage like the Lio dao of the Khitan)
Campaigns
For the Romains campaign I suggest the Aegidus campaign from Manu la Capuche, also he have released a coop version of this campaign this days.
Vandals : of course, the Genseric scenario is too short for their journey. Mixing the Alans is good because without the vandals I don’t know how to make a campaign for them.
Saxons : new civ new campaign. But I don’t want a campaign against Charlemagne, it’s better to put them in England against the Celts.
For the name of the DLC I suggest : Barbarian Invasions I made a topic about this : The future of Roman civilization in AoE2 after Chronicles + DLC and marketing proposal
I suggest that this DLC give access to the romain civilization for those who don’t care about AoE1 and don’t want to buy Return of Rome just for the Romain.
Clovis Campaign
I have made a concept of Clovis Campaign
The man who found my country. In this time the franks were not the mighty knights there were footed soldier who throw axe (la francisque !). The campaign can be related by St Remigius, Bishop of Reims who convert Clovis. This campaign talk about the combat of Clovis and his progressive adoption of christianity.
Maybe in this campaign you can have the axe thrower in the barracks and the knight line in the castle.
1 Battle of Soissons : he fight Syagrius the last roman here. Also don’t forget to talk about the Vase of Soissons in the cutscene : Souvient toi du vase de Soissons ! (Remember the Vase of Soissons)
2 battle of Tolbiac : he fight the Alamans and chose to convert to christianity here. Also you can conquer the thuringian kingdom (your mother was thuringian) In the end cutscene talk about his baptism to christianity in Reims here.
3 Fight against the burgundian : he fight the burgundian, here the reskin of the burgundian Coustillier in a axe rider in Aegidius campaign can be useful.
4 Battle of Vouillé : he fight against the Wisigoth. Now Clovis is a catholic christian and can sell to his new gallo roman catholic subdjet that this war is a religious war against the arianic christian wisigoths. In this scenario you have option to beat this wisigoth making you allyes. Yo can let your frankish warriors who are still pagan to loot the church to have resource or you can protect the church to gain support of the local gallo roman catholic population (you gain legionary and centurion), but if you support the christian your frankish pagan warrior can revolt.
5 Unification of the Franks : There is various frankish kingdoms in this time, in order to unify the frank : assassinate the other frankish kings !