On the planet Neptune, many years into the future, a fierce battle of wits is being fought. Neptune has now been colonised and a rather largish space station built to house its immigrants.
However, nasty aliens are determined to put a spanner in the works. For some reason best known to themselves they have planted a huge bomb somewhere on the station as an act of gratuitous interstellar terrorism. This bomb is so massively big that if it explodes it will not only destroy the space station but will also turn the planet Neptune into mere wisps of hydrogen and ozone as its particles are spread across the cosmos.
This is all a bit worrying. The inhabitants of the space station have been evacuated to a nearby asteroid arid now it's just a waiting game. Gone are the days when highly skilled human bomb disposal experts were sent to risk their lives. Nowadays everything's automated. Arnold (which is a very nice name for a robot) is a mechanical disposal droid which is specially programmed to disassemble dangerous bombs. This droid has been sent into the space station on Neptune to locate and defuse the bomb before it's too late. However, it's still up to you to control Arnold and guide him through the corridors and rooms of the station in the quest for the bomb.
Those interfering aliens have set a timer on the bomb. You have around 999 seconds in which to locate the bomb and render it harmless. Not content with just sitting back and waiting for the big bang, the aliens have also sent in their own saboteurs who will do their utmost to get in the way of your efforts. These irritating creatures will sap your droid's energy if they get too close. They can be destroyed by Arnold but will re-materialise after a short time to renew their attacks.
Arnold has been equipped with a nifty laser which makes short work of any marauding nasty. However, the droid has only a limited amount of power so indiscriminate blasting will wear the laser out quite quickly. The droid also has a certain amount of energy which it uses to move around the space station. Each time one the of the nasties gets too close to Arnold, some of this energy is lost. This is represented by a blue wavy line at the edge of the screen. Once all four lives have gone the game is over and you can enjoy the planet's destruction from the safety of the control room.