After 20 years in space, the Orion has finally accomplished its task of galaxy mapping. Only one small nebula remains, but while making the intergalactic jump, the Orion is taken over by an alien race known as the Zimen.

In an attempt to get rid of the Zimen, the players control four robots - Captain Slog, Plot the Navigator, Engineer Knut, and Able Spaceman Bodd - which they use one at a time. Each robot is situated in different areas of the ship. Some robots can easily navigate their way through the maze of 230 rooms, while others are temporarily trapped in their rooms.

When a robot comes into contact with the Zimen, its energy is quickly drained. When all of its energy is depleted, the robot will stop functioning, and the only way it can be restored is if a passing robot transfers its energy with the non-functional one.

The Zimen materializes suddenly in the Orion's passageways with deadly persistance, and can easily trap the outnumbered crew into a corner. To help them, the robots can throw bouncing bombs at the Zimen, gaining points when they have been destroyed.

Control panels scattered throughout the ship give a robot access to code screens. When decoded, these will unlock matter-transmitters and lifts, meaning that the robot crew can move through the ship and closer to the ultimate goal: locking into the Bridge Computer. When all four have done this, the Orion will be safe.