The Diplomacy gametype is a user created "custom" game with a set of rules in a FFA to be followed to play the game as a real world scenario of deceiving enemies, making valuable alliances, making "declarations" of war, and eventually being the last one standing, however, the game can be voted to end if an alliance claims "victory".
Common rules consist of:
- No attacking other players without declaring war on them in public chat so as to give the enemy a fair chance.
- If a player attacks without warning (in some games this is known as "Blitzkrieging", German for "Lighting War", which is what the Germans used in WWII to surprise and overwhelm their enemies to win), then all players in the immediate area of the blitzkrieger can attack without warning or reason. Commonly, the blitzkrieger becomes "public enemy" or "PE", requiring all other players to attack the PE if they are able. This rule is used to enforce people to follow the rules, as there is no concrete way of stopping people from breaking them. Most hosts make the game a practice game.
- Alliances are encouraged. Some games require alliances be made public, some allow it to be private. Allies are a good way of invading successfully or defending from a stronger enemy.
Common settings are "no fog" or "slight fog", so as to know if someone really did blitzkrieg. All cards are often enabled to allow for interesting storyline twists to occur in the game.
While the exact creator is not known as after its obscure creation other users quickly copied the rules and made spinoffs, the user "Soviet Russia Buddy" takes the most credit for creating the game. His first game was known as "Reality Warfare, A New Way Of Playing", which was then shortened to "Reality Warfare" which its current name is. This can be disputed by Le Count H who was laying the foundation in scenarios in late September of 2012. These were initially unfair due their emphasis on giving nations overwhelming advantages due to their size. His games became extremely popular the following summer. Another user named "Zecit" coined the term "Public Enemy" in his game "Simulation World", which is used in many Diplomacy games. Out of all hosts commonly making these games, he (presumably male) has the most amount of rules and hosts games at least once a day. However, not all of them are rules and rather more creative and realistic additions, one of which is a rule involving capitals, and some are guidelines that can be used to be more "diplomatic". People who have played with him have said they have played that gametype with him for almost 2 years. When asked where he got his possibly original idea, he said he had been playing a 24FFA with no fog when he noticed that everyone had to have secret alliances as no one was attacking anyone.
Currently, many different players host these games. Most of them are 6FFAs, but Soviet Russia Buddy and others host 24FFAs, or sometimes less for scenario diplomacy games. While many players attribute many different users for its creation, many only use 3-4 of Soviet Russia Buddy's original rules, usually copying them word for word. Alternatively, rules are slacked and public declarations are only required if a player wants to be "trustworthy". Many diplomacy games involve a strong element of roleplay, as players play as if they were a character in whichever world the game is set in. This works especially well with maps of universes from fantasy novels, such as George RR Martin's "Song of Ice and Fire".
 Diplomacy mods
The most requested feature from Uservoice, Peace Treaties, has been implemented as a Mod. The Advanced Diplomacy Mod removes the need for players to be "trustworthy", as declarations are not needed anymore, since if you are at peace with someone, you cannot attack each other.