Games in which we create shapes are fairly common, but there is another type of games you can find: games in which you have to delete some shapes.
In these games, you have to delete shapes to allow a fall, a collision or any other reaction which will allow you to succeed the current level.
Often, you removes the shapes with a single click, but once they are gone, they are unable to return. The only solution is to start over.
In these games, all is often a matter of timing. You must delete shapes at the right time to get the desired effect. One second too soon or too late, and it is missed!