Parley is a mini-game in Final Fantasy XIV, available to players upon completion of their rank 15 main quest. It can be played with specific NPCs inside the city-states, or as integral part of quests, by selecting them and choosing "Parley" on the interactions menu.
To parley with NPCs outside of quests, the player must bet one of the specified items, which change from NPC to NPC.
The game of parley is considerably popular in Eorzea and often used as a method of negotiation with the beast tribes, as the rules are known by almost everyone, while few know the beastmen languages.
A grid of 12 panels is randomly populated with icons representing topics of debate. Each icon has a point value, and the player and the NPC take turns choosing said topics.
When a topic is selected, the respective amount of points is added to the score bar, which fills up when added by the player and empties when the NPC gains points. If there are adjacent panels (vertically and horizontally, also wrapping around the borders) sharing the same icon as the selected panel, their values will be added to the total. If, for example, if the grid looks like the following, you would get 6 points by choosing the A2 panel (1+2+3), 5 points by choosing A4 (4+1), 7 points by choosing A1 (1+2+4), 4 points by choosing C3 or C1 (3+1), 3 points by choosing B1 or B2 (1+2) or the face value if choosing any other.
After each turn, panels move from right to left to fill the gaps and the remaining empty panels are repopulated. Each game lasts a different amount of turns depending of the NPC, with harder games usually lasting longer. Sometimes, an ability will become available, with effects such as doubling the face value of all panels. The difficulty of the game is determined by the NPC and the item offered to initiate the Parley. While the player and NPC take turns, they may move around or perform motions to indicate that a discussion is occurring. Victory is achieved if after the last turn, the score bar is above the yellow mark.
If it's a quest, the reward is often progression on said quest.
When playing with random NPCs, the reward is simply a new copy of the item given to him at the beginning (bet a potion, get two potions). Loss means losing said item. However, if the player wins with a good play (making lots of combos or racking up many points on a single turn, for example), his winnings may increase and he may be awarded with additional items or information.