This is very important for me. Because if there is a very good city defence like in CIV5 and a large army is needed to take town, I won't play this new civ. And so I won't follow all the thread of the forums to be inform and prepare.
Here are some of the big changes that we know so far about civ6 combat and cities:
- Walls are now required for the city to have a ranged attack. So a new 1 pop city will not be able to range attack anymore.
- Walls do add a second "health bar" to cities. The attack will need to bring the walls down to 0 HP and then take the city's HP down to 0 before taking the city. This will obviously make taking walled cities harder.
- Walls also give the encampment a ranged attack. So a walled city with an encampment will have 2 ranged attacks
- Melee units now require a "battering ram" support unit stacked with it in order to attack walls.
- Districts mean that battles will most likely take place further from cities since players will want to defend their districts.
Of course, it will come down to what the attacker has and what the defender has. It looks like cities without walls will be easier to take since they won't have a ranged attack or extra HP. So attacking cities without walls will most likely be easier in civ6 than in civ5. Conversely, walls adding an extra HP bar and a ranged attack will mostly make walled cities tough to take unless you have a lot of battering rams/catapults.
Personally, I think these changes make a lot of sense because they are more realistic. Historically, unwalled cities were more vulnerable whereas walled cities required tough sieges.