See information provided with the package. It is played by controling the motion of blocks which continue to fall from the top of the screen. One can move them left and right, as well as rotate the jewel segements. The object is to get the most points before the grim reaper ends the fun.
Death happens when the screen is no longer capable of holding any more blocks.
As the game progresses, and more jewels are removed, the speed of the game will increase. This is measured in seconds of delay between steps of block motion.