Click to start (I don't know why it requires a click before listening
to keyboard events.) Press 'n' for a new game. Press 2,3,4,5,6,7 or
8 to change the number of colors.
Two or more adjacent (right, left, above or below) squares of the same
color will disappear when you click on them. Blocks will fall
downward into the space. If an entire column is empty, it will slide
over to make sure there are no gaps. The goal is to clear as many
blocks as you can. There is no guarantee a puzzle is solvable.