Shanghai Solitaire is a mahjong solitaire game developed by Oberon Media in July 2007. It features a set of Mahjong tiles arranged in six different tile layouts. Each is stylized to portray the object or animal it was named after. The different tile layouts are Cat, Crab, Dragon, Fortress, Spider, and Turtle. Players are also given a choice to change the background color or the playing table. Players are also given four choices as to the design and color of the Mahjong tile sets.
Shanghai Solitaire is played with 144 tiles—each with their own image and part of a pair. Each image appears four times. However, one may not be a pair to the other. This might result in unsolvable games. The tiles are arranged on the board according to the design, one on top or beside another. The objective of the game is to remove all the tiles from the game by clicking all matching pairs. To be able to click a tile, it has to be free from any hindrance. That means that it cannot be under another tile. If a tile is between two other tiles, then it is not free. It must be on the top and on the edge. To make a pair, the user must click two identical tiles successively. Thus, to remove tiles from the board, the tiles must be both identical and free.