The Shanghai MahJong board is composed from 144 tiles,
each tile has a different images, usually numbers, seasons and flowers.

The tiles are arranged in a grid, which is usually higher near the center (depends on the selected layout).
The board layout is generated randomly by the computer, The Layouts can differ in pattern, size and height. There are hundreds of different layouts.
some of the implementations also have a time limit of 5-15 minutes to finish the board.

The goal is to clear the board by removing all the matching identical pairs from the layout.
A valid pair consists of two tiles which are both "free" and "identical" (or of the same type).

In more details, you can remove a pair of tiles if the following condition are true:

• The tiles are identical (e.g. 4 and 4, West and West, etc.)
• All of the seasons and flowers can be matched with each others, they don't have to be identical.
• Each tile of the pair must comply with the following rules :
  - No other tile is lying above or is partially covering it
  - No other tile is lying to the left or to the right of it

Each tile appears four times in a standard solitaire mahjong game.
In some implementations the Flowers and Seasons tiles will appear only once each during a game.

Because every tile appear four times, you might match the wrong pairs,resulting in that you will later find yourself without any more matching free tiles.
Some games allow you to undo your moves, so you can try and guess again which pair is the right one, but some implementation will just end the game because it just becomes unsolvable.


While MahJong Solitaire sounds like a game of luck, some strategies will give you much higher chances of winning:

• First, try to remove the pairs that will unblock the most tiles.
• When the board still has Tall stacks and long rows, try to make an effort to eliminate them first.
• Each tile appears four times, When removing a pair, try to choose wisely, if you have 3 free tiles from the same type, look ahead and try to figure out which 2 tiles will be the better choice.
• If all the four tile from the same type are free, just remove all of them.
• The computer hints (in games where it is available), doesn't always show the best move, it will probably show the first move it can find.
• Try to identify as many matching pairs as possible and plan which tiles you will need to match before they can be free.