The Krion Conquest (Nintendo NES)

Once upon a time, long long ago, the world was experiencing great ruin. Enormous animals were bestowed upon the earth to create terrible pain and hardship for the people. The people were desperate, so they called upon the Old Witches' World for help.
Thence came Francesca, a gracious witch with great powers. She fought and saved the world from these terrible creatures. The land began to flourish again and the people worked peacefully together to rebuild their wonderful cities. All was well.
Now, we too are experiencing serious turmoil. Terrible horrid beings called Krions have decended upon our planet. We are prisoners and we are losing hope. Francesca, we need you. If you are out there, please come.