The rules of Classic Mahjong online game are very easy. Use mouse to match open pairs of identical tiles and remove them from the board. A tile is said to be open if it can be moved either left or right without disturbing other tiles (opened tiles are highlighted).
All four flower tiles in flash game are the identical, and all four season tiles are the identical too. So any open pair of flower or season tiles can be removed from the board.
This online game has 60 levels, so you'll have chance to play your favorite game a lot.