By successfully completing a game of Mahjong, you are awarded 3 crowns. By accruing crowns, your Dragon Level increases which unlocks new content.

If you access the Mahjong menu bar and select the Board tab, you can see what will next be unlocked. The vertical gold bar to the left of your Dragon level will show your current progress and how far out you are to unlocking the next content.

If you are itching for some new content, a new tile set for example, select the Tiles tab and the next set of tiles to be unlocked will appear as a mystery grayed box with a crown icon and a number below it. This number is the number of crowns needed to unlock this set.