You've run up a nine figure tab at a hotel on the planet Babylonia, but you don't have the cash to pay the bill. Never fear, the Mutual Brothers of Credit Association has a solution to your problems. They want you to visit the planet Cymarron and pick up some "valuable items" for them. Cymarron is a sister planet to Babylonia, charitably described as "less fun to visit than an afternoon in Dirt Hole, Arizona."
They Mutual Brothers even let you keep your meager fund of credits so you can buy supplies from the "Pawnkeeper." Provisions you can purchase include a Stinger Needle Gun, Mithril Tee-Shirt and Mac Macs Travel Burgers. After concluding your negotiations with the Pawnkeeper (or getting tossed out for excessive haggling), you head for the spaceport to catch your flight to Cymarron. Before departing you will select which entrance of the Vaults you will use.
Once you reach the Vaults of Cymarron, you must move from room to room searching for valuable items. Along the way you will confront monsters of varying ferocity (and strength, depending on which of the nine difficulty levels you selected). You will also find computer terminals that provide clues to aid your search.
Each room is graphically depicted, showing the walls and doorways as viewed from directly above. Monsters, objects and your character are also shown on screen. You move your character around to screen to exit doorways, pick up items or get into fighting position.