Use the Mouse to move the wallbuilder. Click to start building a wall. Press Space to change between vertical and horizontal wallbuilding position.

The rules are simple:
Trap the J-atoms into smaller spaces in order to make at least 75
percent of the camber disappear. You can check on your progress by
looking at the area cleared at the bottom of the screen.

The wallbuilder can sustain only a limited number of atomic hits. Each
time it is hit, it loses one chamber life. The number of lives left is
displayed in the upper-left corner of the screen. If two atoms are free
in chamber, a wall in progress can be hit once. A second hit by a
J-atoms ends the game. You are allowed an additional hit for each atom in the chamber. For example, at level 7, the wallbuilder can sustain six hits, with the game ending on the seventh.

A game ends when the wallbuilder is destroyed by atoms or when you run out of time.