it's easy to learn to play and fun to master gameplay, but it's still a challenge for you to play with. because it will discard a block if you haven't used one block in specified seconds, and one random cell of gird will be invalid at the same time.
Drag one block and drop it into the gird to create and destroy full lines both vertically and horizontally, keep the grid from filling with blocks.
One of the invalid cells of grid will be recovered when a line destroy.
Enjoy the puzzle game!