In order to get all games of majong done you need to press

at every hidden object scene. After you do that a game of majong will appear. Click on 2 matching tiles that are both lightly colored and they will disappear. Finish all the tiles and you will be done with one of the 20 games there are in the game. If you get stuck you can shuffle the board with the string on the right side of the screen. The last game of majong will happen near the end of the game. After all 20 you are done.
Ding! Congrats the achievement is yours.
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