The colonisation team had almost completed their task when a nuclear power unit went super-critical. The base had to be abandoned. It is now down to you to make the planetoid safe again! You do this by moving around the planetoid, “decontaminating” it – collecting all the radioactive objects – and when each screen is cleared, it becomes a Safe Zone. A screen which no longer exposes you to radiation – something which happens all the time in non-safe screens. Of course, there are highly radioactive life forms to avoid as well. Once all screens have been made safe, you complete the game. You have a few spare radiation suits (lives) on the start screen. Without a suit, you are highly vulnerable.