This is a Mahjong game, a one-player game.
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