Heh, I like the way you put it Imp.
And yes, it is a full diplo game. Every game I played on was a full diplo unless explicit specified there is no diplo at all or only anonymous diplo or only game interface diplo (the RB so called AI-diplo).
I did not mentioned it, nor put it as a rules, but anyway I will say this here more like guidelines of good manner when it comes to diplo. Use it or not at your own discretion. Those are few things I collected as a common wisdom through the games I played and I find logical.
Negotiating. Negotiating or agreement or even talking this-game-specific things before actually meeting someone in-game is not nice IMHO. What is the fun if you tell your good on-line or RL buddy before even the game starts "Lets be friends and try to screw all the other guys"? What is the game logic in that? What logic can be if civilizations or rulers who never meet or know where the other is and really dont have a way to even talk to each- other by the game interface (before meeting some civ in-game, you cant open a diplo window with it, right?) to start plotting or negotiating? How you are supposed to tell someone you never met where your nation is or which are it's neighbors?
So in brief, negotiating or exchanging game-specific information before in-game contact is considered poor sportsmanship.
Trustworthiness. Different players have different understanding about how strict their agreements should be followed. There is no formal penalty or reload or something for breaking a promise or agreement in-game. So someone can easily abuse the trust of someone else. And this is just a game, so someone may say "well, this is my role I choose in this play" and this is OK, but then, he must not be surprised if few more righteous neighbors put away their own feuds or even their own in-game interests and come after him. Moral police in-game? Well, this is how they feel and "this is the role they chosen in this play"
Or dont be surprised if you take the word you given not so strict as a law or an oath, the word goes around and even if not in this current game, but you start to find it very difficult to get any agreement. And being the only one who cant get security through diplomacy leaves you the only prey in open hunt season
Reputation is built hard and is lost easily.
Activity. Being active on the diplomatic front can be a strong help for your in-game plans and play. Of course, it is easier to achieve your goals with kind word and a big stick, than only with kind words, but on the other hand - pen is mightier than the sword. Active diplomacy can drive you a long way. Being talkative as a fish or a tree, you will need a really big stick to compensate for the lack in talking.
Ways of communication. Elkad brings good point that what seems like the most normal way of communication for one, can be no way to communicate at all with other. For example, I never ever even claim my leader on Civstats. I use it only as a turn tracker and load it from a tab with favorites to see if it is my turn to play. I can be most surely be reached by PMs or e-mails if we had exchanged e-mails. Generally speaking, it is a good practice to send an in-game message saying just maybe "Hello, I had sent you a PM on CFC site", or "You have a message on Civstats", or e-mail or whatever. Because everyone sees in-game message at most the other day they are sent. And then he will know where to look for his full message. Diplo-messages are sent by opening a diplo window, you type your message in the text field and then hit ENTER. THen you click "send offer". There is one trick in sending in-game messages. Sometimes they just did not arrive if it is only a text in the diplo-screen. A way to make almost 100% sure they will be delivered and the other player will see them is if you include something else in the diplo-offer. Being it a 1 gold piece, or a map for map offer if it is no longer a relevant.
Agreement duration. It is not fun to say to someone "We will be friends till the end of time". This mutilates the whole idea of diplo between thinking humans. Say we have a Non-aggression pact (NAP) for 10 or 20 turns inclusive, or we have 50 turns NAP, or we have a revolving 10-turns NAP which requires the one who wants to end it must warn the other party about this 10 turns in advance, but do not say "we are in peace and love till 2050AD". It is unrealistic and dull.
Clarify. Spell out what your agreement includes if you want to be sure you have strict agreement. NAP can means a lot of things. Someone may see a lot of things as aggression. Like spending espionage on him, or scouting his territory, or settling towards him, or building culture to flip tiles, or even voting against him in an AP vote. So then there might be accusations: "But he broke the NAP". Where if you specify "NAP means no party will declare war to the other" this is already clear what you agree on. You can use espionage, you can settle wherever you want or can, as long as you dont declare war to the other.
Or if you agree to Open Borders, but then you are unhappy that the other guy is scouting your territory, or sending military units through your territory to attack neighbor or a barbarian city? Well, tell those things in advance. Say: "OB only for trade routes. No unit will enter the other's territory". Or: "OB with only non-military units tresspassing" etc. etc. Clarify and specify. So there be no sore feelings later on.
Think and consider. Think when making agreement where your agreement with one may come to conflict with agreement with other player. You cant really sign a NAP with one guy and then sign mutual protection pact with another. What you do if the first guy invades the second one? Which agreement you are going to honor? You will be traitor in at least one of them's eyes. Way better is to say in advance: "I can agree to Mutual Protection Pact if this not include nation X, because I already have a NAP with it". Then it is up to the second guy to decide if this works for him or not.
This is what comes to my mind at this moment. I apology in advance if this is common knowledge for some or all of you. I just though it might be of help to someone new to this stuff.
