Why do people like the game Diplomacy?
Diplomacy is a strategic board game that does not rely on dice or other game elements to introduce randomness into results of gameplay. In the game Diplomacy, players negotiate, form alliances, and betray each other in an effort to occupy geographic provinces and control of "supply centers" to win the game. 

People like playing the game Diplomacy because it is unique compared to other strategic board games. In Diplomacy, all players submit their "orders" to move their pieces around the board into a box and those orders are adjudicated at the same time, making it difficult to gain an advantage over another player without communicating and planning out moves with other players. The only variable in the game is each player's ability to convince the other players to do what they want. Some people find this aspect of negotiation-based game play compelling, while others find the "anything goes" nature of these negotiations repelling. Therefore, Diplomacy is sometimes referred to as the "game that ruins friendships."