Rock-Raiders  

The eponymous Rock Raiders were a team of miners that searched for energy crystals in the underground. They had several specialized mining and transport vehicles at their disposal, and were based at various locations around Planet U, where they processed rocks to extract the powerful Energy Crystals with their refinery stations. During their excavations, they would occasionally encounter Rock Monsters (included in two different sets), Slimy Slugs, and numerous other monsters, who would often attack the Rock Raiders or their bases, usually for Energy Crystals (although some, like Spiders and Scorpions, were merely aggressive towards the Raiders).

The humans are a group of astronauts that have journeyed to Mars in search of powerful yellow-green energy crystals found on the Martian surface. In the storyline, the humans are mining the crystals for a new source of energy, as Earth is experiencing an energy crisis. Unfortunately for the Astronauts, the Aliens are also seeking the crystals for themselves.