A river of blood is a way of playing mahjong in Chengdu, Sichuan, and so is playing the missing door. A river of blood means that if there are 1 players in a game, the game is not over yet, and it is not over until three players are hit. A river of blood basically means this. In fact, you can learn these basic games on special blogs or forums. Recommend a /rhdmj/392.html that I often browse. I hope it can be adopted. Thank you!