A Guild is a build tree. It has three levels. It can be associated with city, castle, or both.
You may have only one level 1 guild of any kind per city.
You may have only one level 2 guild of each kind per faction.
There can be only 1 level 3 guild of each kind in the whole game. This means you must compete with the other factions to attract a level 3 guild.
Specific types of guild can be restricted to specific factions.
It can be used for recruitment of units or characters.
It can have benefits relating to trade, happiness, law, public health, unit experience, or character statistics.
It can trigger events, perhaps other build trees.
To be built, the player has to receive an invitation from the Guild, meaning that you cannot start this build tree anytime you want.
You get invites from guilds by scoring "points" with them. For example, when you recruit a merchant, your score at the merchants guild (in the recruiting city) increases by 10. Each city keeps track of its score at each guild independently of your other cities.
The points accumulate until you hit the thresholds. The threshold for a guild house in the city is 100. As soon as you score 100 points with a guild in a city, they will approach you about building a house there (provided you have the money to build it). If you reject the offer, your score with the guild takes a penalty, and they will approach you again if the score reaches 100 again. If your score with a guild reaches 250 in a city, and you do not have a master guild with them yet, they will ask you to host their master guild. If your score reaches 500 and the guild hasn't built a world headquarters yet, they will ask you to host their headquarters. Every turn after the 25th turn, the normalization process takes place. Normalization is where you lose 1 point with every guild in all your cities. So if you train a spy in a city, 10 turns later the score boost is gone. You need to rapidly earn points with a guild before the normalization process cancels out your score.
Guild specific missions are possible, and if used can contribute to the points process for the next level of guild.
The role-playing opportunities should be obvious: guilds represent a whole new level of interaction with the game, where your actions directly influence the development paths that can open up to you, and a new and potentially non-military way to compete with other factions.
Some specific examples of what Guilds could represent.
Micro-factions
Guilds could easily represent small nations, regional powers or small tribes that are now subsumed in the Eleutheroi or as part of the various playable factions. The following list is not exhaustive or comprehensive, and I am not for a moment suggesting that this many separate guilds be created (at least not at first). But one or two of the best candidates could be used to represent micro-factions that may throw in their lot with one or more of the playable factions, depending on their actions.
To develop an example, let's take the Daha. Dahae skirmisher cavalry and Dahae riders are common mercenary units in the eastern part of the map. Many factions can also recruit Dahae units directly depending on their MIC and Government type. There is also a good unit of Dahae Noble Cavalry.
If there was to be a Daha 'Guild', what would happen is that the Dahae units would disappear from the normal recruitment system. Factions would have to earn points with the Daha in order to attract their support. This could be by hiring low-level Daha mercs- once you have enough Daha in your army, you have attracted the attention of the Daha nobles, who wish to offer you their qualified support. You build a level 1 Daha Guild (it wouldn't be called that
), which allows you to recruit Daha skirmishers directly, and maybe has some other effects associated with it (culture, happiness?). To reach level 2, you have to recruit lots of Dahae, and maybe complete a mission for them (conquer a specific territory?). Then you get the Dahae Riders. The best unit would be reserved for level 3 and represents the total commitment of the Dahae people to your cause. Although any other faction that has managed to attract level 1 and 2 Dahae Guilds can recruit skirmishers, only you have the mighty Dahae Nobles on your side.
Again, these examples are only some possibilities.
Tribes
Iberian Tribes (17 units)
Belgae (4 units currently)
Daha (3 units)
Carnutes (1 unit)
Ordes
Chatti
Goidelic (5 or 6 units)
Skuda (4 units)
Aursa (2 or 3 units)
Boii
Cimbri
Teutones
Bastarnae
Thracians (4 or 5 units)
Smaller Kingdoms, Confederacies and Polities
I see this group as subtly different than tribes. These are more advanced societies, more tied to one place, and could have much more specific triggers, or be for certain factions only. Being offered a guild by a small kingdom represents an alliance or treaty, and could have significant impacts on public order, trade, culture penalties etc. The fact that you would have to work to earn the trust and support of a smaller kingdom while balancing their demands against those your other 'guilds' would be role-playing heaven. At level 3, perhaps some of these kinds of guilds could offer you recruitable generals to join your family.
Illyria
Maccabees (wouldn't this be fun?)
Galatia
Commagene
Mauryan (9 units)
Persians and Medes (7 or 8 units)
Massylia (if it doesn't make it in as a faction)
Massaesylia (ditto)
Garama
Mauretania
Nabataea
Samnium (2 or 3 units at least)
Megale Hellas The Greek City States of southern Italy weren't automatically aligned with Pyhrros!
The use of guilds to represent semi-playable micro-factions potentially blows the lid off of faction limitations. There is also the possibility of a system of faction development like the one Dominion of the Sword is working on, which could be tied into the micro- and intra-factional guilds to determine how your faction changes over time.
Intra-factional Structures
Here I mean something quite different than above. Even within a solidly homogeneous faction, there are elements that lend themselves to a Guild build tree. A generic one would be Nobles- why should you be able to count on the unequivocal support of the nobility of your kingdom? What if you couldn't? Many factions have important elite units that represent the fighting nobility. Recruitment of these units could depend on the Nobles Guild build tree, which would have to be specific to each faction ( i.e. only the Parthians could have a Parthian Nobles Guild ). If we're talking Macedonians, the Hypaspistai and Hetairoi would be available to you only after you've convinced the nobles that you are worthy of their support, and so on.
Nobles of any faction
Koinon ton Makedonon - you may be King of Macedon, but can you keep the support of the Assembly of Macedonians? Could be tied to Pezhetairoi recruitment.
Greek Leagues - if the Aitolians and Achaeans don't make it as factions, they can be political organizations that you must conciliate to keep control of Greece. Could be used for Iphikratid Hoplites.
Tribal Confederacies
Comitia Centuriata or Concilium Plebis (Romans only, of course)
Druidic Colleges (Isle of Mona) (Celtic factions, maybe Casse only?)
Spartan Agoge (I think that this would be much better as a guild than a Gov type. Could recruit Spartan hoplites.)
Current Build Trees
Some of the build trees currently in place in EB1 could be turned into guilds, representing the contribution of someone other than the faction leader to the development of the nation.
Temples and Religion (level 2 recruits an agent?)
Games and Festivals (level 2 recruits an agent?)
Schools
Slave Economy (decreases build times and costs, increases unrest?)
Kleruchies (tied to Kleruch unit recruitment?)
Machimoi
Concepts and Ideologies
This is the least-developed part of my thinking but potential the most powerful game-play tool. Guilds could be used to represent various kinds of ideas and movements that transcend normal factional allegiances. Whatever the religion system of M2TW becomes, a related guild system could be developed that would allow you to role-play your characters to a whole new level. If, as has been suggested, religion turns into something to do with political ideology, you could have the governor of a city that builds a city popular assembly be offered the Democracy Guild, with who knows what affects?
Pan-Hellenism
Political Allegiances
Reforms, Uniting Events
Time of Bondsmen/Time of Soldiers
It would not be necessary to choose between different kinds of guilds or concepts: EBII could have a few guilds that represent micro-factions, a couple that represent intra-factional structures and one that stands for an abstract concept.
I think that there is a lot of possibilities here, of which I have only scratched the surface. I am sure that the EB team has already had some great ideas about this, but I hope by throwing this out there that it might be of some help and interest.