The CIMA aliens feed on humankind's hopes and dreams. They build elaborate mazes and trap people inside them as a way of producing their food. A force called "Gate Guardians" was created to protect the population from this menace. Three Guardians were on a train delivering settlers to a distant station, when suddenly a portal for another dimension appeared and transported everyone to a strange moon-like place. The Guardians must find the way home and bring back safely every passenger. (Mobygames)