In ancient china, there was an intelligence-boosting game called Huarong Trail or Chinese Sliding-Block. It is extremely difficult so it’s been listed as one of “the top three incredible intelligence games in the world”. Along with other traditional Chinese intelligence-boosting games like the tangram, it’s nicknamed “Chinese Difficult Problem”. There are lots of changes and strategies with great unpredictability in the game. The players will never get bored.
The name of the game comes from the story from Romance of the Three Kingdoms. The story happened during Battle of Red Cliffs in the 3th year of Jian An in the East Han Dynasty 208AD-- a well-known battle in Chinese history. Cao Cao (a warlord and the penultimate chancellor of the Eastern Han Dynasty) was defeated in this battle, and escaped to the Huarong Trail, in which he encountered Guan Yu(a general serving under the warlord Liu Bei during the late Eastern Han Dynasty of China). Because Guan Yu remembered that Cao Cao used to treat him well during old days despite he was a general of enemy of Cao Cao, Guan Yu spared Cao Cao's life. The largest block of this game is named Cao Cao.
According to this story, Chinese people invented this game, which has a chessboard with 20 small checkers, symbolizing the Huarong Trial. There’s a two-checker-long exit at the bottom of the chessboard for Cao Cao’s escape. There are ten chess pieces of different sizes placed on the chessboard, respectively symbolizing Cao Cao, Zhang Fei, Zhao Yun, Ma Chao, Huang Zhong, Guan Yu and four soldiers.
There are only two unoccupied checkers on the chessboard. The rule of the game is to move the pieces by using these two checkers to help Cao Cao reach the middle of the board bottom for his escape from the initial place in the fewest possible steps. You can’t move the pieces by skipping. Among all, Cao Cao is the only chess piece allowed out. The player is expected to move Cao Cao out by using the fewest steps. There are dozens of arraying methods in the game of Huarong Trail.