Tap any uncovered tile to send it to your rack. When three tiles in the rack form a set they clear: three of a kind (a pung), three tiles of one suit in a row (a run such as 4-5-6 bam), three flowers, or three jokers. A joker fills in for a missing tile.
Mahjong Triple is a one-player matching game played with the real 152-tile American set. Tiles are stacked in layers; you may only pick up a tile that has nothing lying on top of it. Picked tiles wait in a rack that holds seven. As soon as three of them make a legal group they clear and the rack makes room.
The groups are the ones you already read off the National Mah Jongg League card. A pung is three identical tiles. A run is three tiles of the same suit in sequence, the shape behind every consecutive-numbered line on the card. Flowers clear as a group of three, and jokers act the way they do at the table: they stand in for whatever tile you are missing. Practising these shapes here is the same eye you use when you sort a rack and look for the hand you are building.
Every deal is built backwards from a solution, so the tower can always be cleared. If you fill the rack without making a group, nothing is lost — Recall puts the last tile back, Shuffle re-deals the tiles that are still stacked, and Hint lights up three tiles that make a set right now. There are eight levels, from a 33-tile warm-up on two layers to a 138-tile tower on four. Each is timed and rated from one to three stars, and your stars and unlocked levels are remembered on this device.