The Diplomacy gametype is a user-created custom gamemode. It consists of a set of rules, enforced by the players themselves, in a FFA to be followed in order to play the game, with the objective of involving complex social deductions. Roleplay gives depth in the form of realpolitik. In other words, deceiving enemies, making valuable alliances, making declarations of war, and eventually being the last one standing, however, the game can be suggested to be voted to end if an alliance claims victory or a consolidated standstill disengages the players.
- Attacking other players must require an explicit declaration of war on them in public chat, so as to give the enemy an opportunity to reposition armies and prepare. As such, both sides have to wait a turn to attack after the war declaration. By extension, attacking a player without this warning is forbidden.
- Alliances. Some games require alliances be made public, some allow it to be private. Alliances are a good way of obtaining higher income or clout successfully, or defending one's own income and clout from stronger enemies.
- Maximum number of alliances a player can have (Even if alliances are encouraged, there's sometimes a limit. This is done to prevent the game from progressing too slowly)
Other possible rules consist of:
- Forbidding gangbanging (refers to a disproportionally powerful coalition attacking a much weaker one. Often a single and isolated player cannot defend himself from several players. This rule exists to prevent the game from collapsing into a meta FFA since players lose their power to enforce diplo rules.)
- Claims (Claiming means stating ownership over bonuses on territory not fully owned by oneself. Often, claiming doesn't need to be respected, but it's usually done so as to peacefully negotiate partitions.)
- Casus belli(Sometimes, players need to provide a reasonable justification for war. This is done to increase engagement and indirectly validate the rules. Examples include disrespect of claims and unwillingness to negotiate, or one's ally being at war.)
- Roleplay (Roleplay increases engagement and validates the rules.)
If a player breaks the custom rules of a diplomacy game, he isn't breaking the actual Rules of Warzone. He only becomes a PE.
 PE (Public Enemy)
Players who break rules in a diplomacy are often called a "PE", which is short for Public Enemy. Which means they are no longer entitled to protection provided by the rules themselves. As such, all players who are adjacent to PEs are required to attack the PEs effective immediately. Usually, players in wars not related to the PE are suggested to agree to a ceasefire in order to deal with situation. Players who do not border the PE but are at war with somebody who does are demanded to agree to a ceasefire. Players who refuse to attack a PE or are offering assistance to a PE will become a PE himself.
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 mode. His first game was known as "Reality Warfare, A New Way Of Playing", which was then shortened to "Reality Warfare" which then evolved to its current name. This can be disputed by Le Count H who was laying the foundation in scenarios in late September, 2012. These were initially inbalanced 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 every modern diplomacy game. Out of all hosts who commonly made these games, he (presumably male) had the most amount of rules and hosted games at least once a day. However, not all of them are rules and are rather 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 more than 2 years. When asked where he got his possibly original idea, he said he had been playing a 24 players FFA 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 used to be 6FFAs, but Soviet Russia Buddy and others used to 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, howver not 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 in which the game is set. 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 and Diplomacy mod remove 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.
Warning: As of November 2018, there are bugs with the Advanced Diplomacy mod. Use the Diplomacy mod instead
Common settings are "no fog" or "slight fog", so as to posess the necessary knowledge to enforce the rules. Many cards are often enabled to allow for interesting storyline twists to occur in the game.
Most diplomacy games in the present day are multi-day games, making them hardly enjoyable. However, diplos often have many players. Real-time diplos often have high boot times, allowing players to engage in social deduction more so than actually strategizing during their turns.
Many hosts make the game a practice game.
 Card farming
Given the difficulty of obtaining cards during long periods of peace, sometimes players will engage in a practice known as card farming. Two friendly players that border each other will agree to let the "planter" take a territory from the other player, only to have the "harvester" take the territory back on the exact same turn as a delayed action.
Note: this will cost 4 armies in a game where one army must stand guard, and 2 in games without it.
Warning: engaging in this practice without making sure both players fully understand it can be very costly, and end up in broken bonuses. It can also be construed as a war by uninformed players so it's very important to engage in clear and constant communication. Sometimes the practice is forbidden due to providing an unfair advantage.