Random Mahjong is a very well done version of mahjong solitaire, commonly known as "Shanghai" from the Activision version of the game. It runs fine on phones, and looks even better on tablets.
Mahjong solitaire is basically tile matching with the mahjong pieces. Random Mahjong have both long games and quick games, with varying levels of difficulty (number of pieces), varying arrangements / formations, and such. The animations are very smooth, and the table "zooms in" as you remove the pieces around the edges. Very nice!
Try the free version, pay for the pro version if you really like it.