In the 1940s, the Nazis built a base on the moon and plan to use a mysterious substance called Lunarium to reduce people's intelligence. However, in the 21st Century time travel has been mastered, as have jet-propulsion backpacks, plus some cataclysmic weaponry and advanced code-breaking equipment. Thus, you are sent back in time to change the result of the war using this technology to find their five rocket factories and destroy the moon base.