The game is set in the near future when the Earth is under imminent threat of invasion from aliens. As the alien ship approaches it passes Earth's last line of defence, a laser facility on the Moon. The laser is about to fire and destroy the aliens when it is sabotaged and malfunctions. The player/engineer has to solve a series of increasingly more difficult puzzles through the practical application of circuit theory under severe time constraints to fix the generator to fire the laser and save the planet from destruction. The game has seven increasingly difficult levels to complete, based around fundamental electronic and electrical circuits typically found on first year undergraduate engineering courses.