1.0. Out of Game Actions
1.1. Screenshot Trading
Screenshots taken in-game of a city, minimap, or anything else are not to be traded to another player either as part of a deal or a gift until the required tech for map trading, Paper, has been discovered by one of the players involved. Verbal descriptions using generalities and landmarks are allowed.
2.0. In Game Actions
2.1. Renaming Cities
Because cities are tradable, refrain from naming a city something that can be confused with something else, such as "8 Gold" or "Theology". Naming cities is allowed as long as it is not for trickery.
2.2. Gifting Units
Gifting/receiving units for the purpose of fighting an enemy while in an ally's territory who isn't at war with them, and then gifting it back to avoid it being killed is prohibited. Gifting units to an aggressive civ and back to gain a free combat I promotion is prohibited.
2.3. Gifting Cities
Gifting a city to an ally when it is about to be taken in war, or to somehow gain an advantage is prohibited. Gifting cities are only allowed as gifts of goodwill, or surrender in war.
2.4. Suicidal Units
Attacking your ally's units or vice versa with the pure intent of gaining experience points, not for war, is not allowed. By suiciding warriors or any unit on each other, you can quickly gain many experience points.
2.5. Gifting and Attacking
Using a unit with multiple movement points to attack, then moving it into another player's territory and gifting it to them (either for them to later attack with the unit another turn or not) is prohibited. Units that have attacked in a turn are not allowed to be gifted to any other civilization.
2.6. New Exploits
This list does not cover all exploits; if you find an undiscovered one, it is your duty to inform the other players.
2.7. Perpetual Anarchy
It is possible to operate in a near-perpetual state of anarchy to prevent losing units due to going broke with high maintenance costs. By revolting to anarchy, and ensuring that the anarchy is a minimum of four turns, no units will be disbanded due to lack of maintenance funds during the anarchy period. On exiting anarchy, there is a one-turn grace period in which no units will be disbanded - long enough to produce more units from forest chops (that get stored-up in the production box during anarchy) and then revolt again. This is considered exploitative.
Playing Guideline: You are allowed to revolt however frequently you like, provided you can pay for your units!
2.8. Unit Gifting Bug
When CivA is at war with CivB, it is possible to gift a unit in a transport to CivA, and then sail the transport to a city of CivB. This results in the units in the city being destroyed, and the city control going to CivA. This is an exploit / bug, and is prohibited.