To win, stack three suits from 1 to 9 in the top-right corner of the table.
Cards can be stacked and moved in the center of the table,
but only if they are of the alternating suits and decreasing values.
The free cells at the top-left corner of the table can store one card of any type.
When all four dragons of a single type are exposed, they can all be permanently
moved to an open free cell by pushing the corresponding button.