I assume there will be some generic civs with the possibility to narrow down their identity through the tech tree, mutually exclusive choices as you advance through the ages.
There will be also asymmetric balance design.
We also know that - tactically - there will be the possibility to hold chuck-points with few units (something from AoE1).
Some random ideas:
Mongols (being confirmed):
- concept: mobile base + mobile units, can thrive with few resources available, adept of optimizations and versatility.
- mobile civ, maybe can pack/unpack buildings (specific to Mongols / Genghis-Han).
- economical upgrade will reduce the cost of units.
- religion: aura-like boosts to military.
- can quickly deploy forward military-focused bases (Ottomans) to support the troops.
- good at raiding enemy territory to plunder resources and enslave troops as peasants.
- weak spot: cannot hold on long face-to-face confrontations.
English/French/Spanish style:
- concept: fortress base + variety of specialized units, no mega unit.
- confirmed to play as AOE2 style (let’s accept there is only ONE civ in aoe2 with minor build order differences).
- that is setting up a parameter around the town center, adept at protecting the area with walls and buildings (reinforced settlements).
- economical upgrades will boost ability to collect resources and drain them faster.
- relies a lot on infrastructure/buildings, losing them makes them weak. Cannot set a strong forward camp easily, but hard to to deal with if they manage to trench in. Can explode if they gain access to many resources.
Indians / China
- concept: fortress + numerous troops + elite mega units.
- it makes a lot of sense to have this civ as it’s visually and conceptually totally different.
- adept of being able to recruit numerous infantry quickly and mega units such as elephants or on-wheels flame throwers.
- religiously adept at boosting training and economy.
- upgrades will boost economy productivity.
- infrastructure wise, they still rely on fortress-style: needs a lot of building types for production and walls; cannot establish forward bases easily.
- weak point: avoid losing expensive units unnecessarily (think Ultralisks in Starcraft).
Nordic / Slave type of civ:
- concept: quick to settle weak strongholds all over the map to harvest resources, versatile infantry troops, prey on the weak, weak vs fortified or prepared armies.
- cheaper town centers, can transform villagers into troops.
- elite units that excels at briefly engaging enemy ranks for burst damage, then wear out for a while.
- goal: control enemy economy with harassment while taking over the map.
- weak point: will tear out in prolonged battles, weak on the defense side.