Use the keyboard A, W, D, S or arrow keys Left, Up, Right, Down, and mouse button - if the game description "Mahjong Black White 2 Untimed" is not stated otherwise.
Mahjong Black White 2 Untimed
Description: Untimed version of Black and White Mahjong 2. Combine a black tile and a white tile with the same symbol. You can only combine free tiles.