Defend yourself and your Earth base from the attack of deadly Acid Rain and pollution spawned mutant creatures called Cloud Hoppers. Cloud Hoppers and Acid Rain fall from a cloud covered, polluted sky and when the Cloud Hoppers land, they move along the surface to attack your defenses. Your only defense is a neutron tank, but you must be careful, as any contact with the Acid Rain or with the Cloud Hoppers is fatal.

This was one of those rare VIC-20 games that actually had both cartridge and cassette releases