Shisen-Sho

Shisen-Sho (四川省, Shisenshō; "Sichuan Province"), sometimes referred to as 'Shisen', 'Four Rivers' or simply 'Rivers,' is a Japanese tile-based game which uses Mahjong tiles, and is similar to Mahjong solitaire. The objective of the game is to match similar tiles in pairs until every tile has been removed from the playing field. Numerous computer based versions of the game have been developed.

Player choose a pair of identical tiles to connect, and the connection path must consist of horizontal/vertical line segments, unobstructed by tiles, and must not exceed two turns. If the requirements are met, two tiles will be eliminated. The player's task is to eliminate all the tiles on the board. The game is over if future moves are not possible and tiles are left on the board, or the player successfully removes all the tiles.^[1]

Since there is only one of each flower and season mahjong tiles, flowers are normally matched with each other, and seasons are normally matched with each other.^[2] Alternatively, when playing digitally, some implementations include extra copies of flower and season tiles so that identical duplicates can be matched.

• Shisen-Sho starting board
• Connected by one line segment, no turns
• Connected by three line segments, same-direction turns
• Connected by two line segments, one turn
• Connected by three line segments, opposite-direction turns

• Mahjong tiles
• Mahjong solitaire
• Mahjong

• Shisen Sho - an open source version written in Seed7