O.K., here's my rules updated according to the suggestions people have been making. I've included most of rsbota's changes, edited for better English. The only change in part (1) is to relax the re-host time limit.
fasquardon
Rules & Recommendations:
Part (1) - stability of the game and the players.
i) Re-hosts & starting:
a) We will wait for no more than 5 minutes after game start (by the host's watch) for players to arrive. If you aren't here by then, tough cookies. Likewise, we will not wait more than 10 minutes before re-starting the game after a crash.
b) Do not select your state before the host.
c) Do not leave the game set-up if someone is downloading.
d) Do not go afk without warning. Try to avoid unnecessary afks. When going afk, an estimated time for your absence would be appreciated. Remember to say when you are back.
e) Do not alt-tab away from CK.
f) If the game is being really unstable, don't take out your frustration on other players, we're gonna be as pissed as you.
g) If a player crashes, the game is rehosted at the start of the next year unless he is in war in which case an immediate rehost.
h) If you know you will be away for a game session, either find yourself a sub, or accept that you will be AI'd.
ii) While the game is running:
a) When the game starts, say "in". Do absolutely nothing with the mouse until the host tells everybody "start". If you click on *anything* before everybody has joined, the game might crash. You *may* chat with others, including private-messages, but as everybody is reporting in, your message might go unnoticed in the plethora of messages.
b) Do not go afk without warning. Try to avoid unnecessary afks. When going afk, an estimated time for your absence would be appreciated. Remember to say when you are back.
c) Do not alt-tab away from CK.
d) DO NOT PAUSE. If you urgently need to get the game paused, ask the host to pause. If the host is temporally AFK or is not able to see your messages, then pause until the situation is cleared with the host. While paused, make sure someone is still manipulating the game.
e) Let a few seconds pass before accepting an annexation offer.
f) Remember to be courteous at all times when speaking out of character. In-character insults are, of course, part of the game.
g) It helps if CK is the only program running, particularly when you are the host. Also, it helps to de-fragment your hard-disk regularly.
Part (2) - game play considerations.
i) Avoiding gamey-ness:
a) We encourage roleplaying. Try to get into the headspace of your ruler, rather than doing things just because they will increase your power.
b) You are only allowed claims on one foreign King-level title and 5 Duke-level titles at any one time. Claims gained by event during the session may be used, but after the session should be edited to within the limit.
c) Catholic states may not heathen bash outside Europe unless they are in a Crusade, and it must aimed at taking Crusade goals and whatever is needed to secure them and make peace offers. Keep in mind that you should offer peace immediately after taking Crusade goals until the enemy accepts.
d)Orthadox states may not heathen bash outside the old Roman Empire (i.e. no further east than Mesopotamia) and Eastern Europe (i.e. no further west than Poland).
e) Players shall not assassinate courtiers inside their own court without stating a good in-character reason to do so first. It is forbidden to assassinate characters inside your court just for reducing badboy.
ii) War and Peace:
a) When declaring war against another player, or an AI controlling the state of a player who has warned the group that they will be absent, the player must publicly declare their war-aims. These may change during the course of the war, but again, they must be publicly declared. If a player is absent for longer than they said they would be, their state is considered an AI one, and other players may declare war without stating their aims.
b) When making peace with an AI controlled player state, be lenient. The definition of "lenient" varing depending on the relative power between you and the AI'd player.
c) When declaring war against non-heathens, the player must give a role-played reason (though it doesn't have to be a good one).
d) It is, as a general rule forbidden to annex another player's vassal, unless he has given you permission - either explicit, by agreeing to it out loud, or implicit, by not DOWing you when you DOW the vassal. However, if you have been at war with someone for three years, and they refuse to make peace, you are permitted to annex vassals. There is no other force-peace rule, apart from occupying someone's demesne entirely.
e) If a war starts, and a player ally is AI'd, it is O.K. to call on them.
f) If you and your allies have no further war-making capacity, make peace. Do not refuse peace-offers simply out of spite.
g) You may not move your troops beyond your borders and toward an enemy *before* you declare war on them.
Part (3) - AARs and Edits.
a) We strongly encourage AARs, as these greatly add to the atmosphere of a game.
b) AARs that are particularly enjoyable *may* recieve a some in-game bonus.
c) Edits to compensate for AI mismanagment may be granted on request. PM the GM with your request at least 24 hours before game start Edits that are granted should get posted to the boards, so that all players may see what was changed.
All rules may be changed according to the will of the majority of the players. 
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