This is a Mahjong game of the Japanese style rule.
The Slider that exists under the screen is moved and the tile is selected.
And the Slider is done in the tap and the tile is discard.
Mahjong is the game to finish four Melds and one Pairs.

Example: [1 2 3][6 6 6][6 7 8][N N N][4 4]

However there is a hand not approved when Chi Pon and Open Kan.
Please note whether there is a hand when you do 1 and 9 in Chi and Pon.
In the rule of the japanese mahjong one or more hands are necessary.
The hand can be made by paying 1000 points and doing Reach.
However when Chi Pon and Open Kan are done Reach cannot be done.
If it is a closed hand high point will be obtained.
About Lost Hand. A hand that is Waiting but cannot be won off someone else's discard due to the fact that the owner of the hand already threw a winning tile in their own discard.
Lost Hand if one in all winning tiles are here even if discard doesn't do the tile which it wants to do. But self-draw is possible even with Lost Hand.
The knack is that Ron is never done by the other party.
Ron is never done with the tile that does Discard.
Please reason the Hand from other party's Discard and win.