The craft can surf along the edge of the room or safety area using the navigational keys. It is moved into the free area with the spacebar at half speed. Pressing the spacebar again produces full speed movement. Points are scored for the areas made safe with slow-drawn areas worth double the point of the fast-drawn ones. Each room has a base score which is doubled if a lepton is captured and this multiplies the area scores. There is a time bonus if the room can be cleared quickly.
The laboratory room is declared safe when all the free leptons are captured or 95% of the free area has been safely enclosed. An extra craft is available after the 3rd, 6th, and 9th rooms. The top ten scores are stored in a high score table.