Vestron

In the intergalactic war, the Amstradian empire has taken over most of the known universe. Earth is still putting up some resistance, but is running out of natural resources. It is discovered that the old mining planet of Vestron contains a special kind of crystals which can be substituted for oil. Retrieving these crystals is imperative for Earth to be able to keep on fighting, so you are sent alone to recover the energy source from Vestron.