Double click on the applet to bring focus to the applet.

Use arrow keys to move the light gray box.

Using light gray box, move blocks so that they disappear.

----------

Rules for disapperring box:

* When green boxes touch each other, the color of the boxes becomes yellow

* When yellow boxes touch each other, the color of the boxes becomes red

* When red boxes touch each other, they disapper

----------

If it is not easy to navigate using keys, change the view point by dragging the scroll bars

shown at the upper right corner to the point where it is easier to navigate