I`m glad to say that almost all the speculations about the capital cities are correct.
There are currently 12 large NPC towns in the game, and we plan to expand that to around 15. Five per race.
At any point player heroes can enter the NPC town in RTS view, and walk around in the vibrant NPC controlled town (u`ll see hundreds of citizens going around their daily business if u visit day time e.t.c)
There will be people to talk to and quests to get.
We are planning to implement trading with-in the NPC towns, allowing player to send a cargo of resources there to trade for more favorable rates. (for example player can sell stone resources at one rate on the market at his own estate, but if he sends a caravan with stone to the NPC towns, it could be sold for much more gold.
Additionally some types of mercenary untis could only be hired in the NPC town.
We also, might create some sort of player auctions in the city - we`ll see about that.
Also player will be able to chat with all the players inside the NPC town.
Now to the main point of this topic - players will be able to attack NPC towns, but it would take 3 or 4 players to attack the city. But rewards for taking down the NPC town, especially the capital city would indeed be great.
We should be able to send a message to nearby friendly players to defend the city, so their army would fight alongside the NPC players.
It`s not confirmed yet, but most likely we`ll restrict players attacking NPC towns of their own race (perhaps some sort of outlaw status)