The evil tyrant Greedy has arisen to control a solar system full of sentient beings. He has corrupted the leaders of each world and thereby enslaved the entire populace. He has also sent his minions in the disguise of planet natives into the worlds to enforce his rule.
A lush forest planet, the last planet in the tyrant's agenda manages to send a call of help to the solar system's little ancient hero before being overrun. However, Greedy has even managed to remove the great hero. Yet, he did not count on the interference of the hero's sun, Ristar.
The player takes control of Ristar in his attempt to liberate the solar system. Ristar can stretch out his arms to grab enemies and summarily headbutt them. His long limbs can also be used to climb up on various surfaces. Being a star adds more features to the gameplay.
There was a lot of changes between regions for Ristar. For example the Ice Planet's (Western's Freon or Japan's Elykiki) boss was a robotic cat. In the Western versions, it was an ice monster. Other changes were made like the story of the Legendary Hero was not in the Japanese version, Ristar was born from the wishes of help from the Elder on Flora/Neer not from the son of a giant handed hero.
Also, the PAL Sega Mega Drive/Genesis has a higher resolution than the NTSC system. Most games just add borders to compensate for the higher resolution. But Ristar is one of the few games that actually takes advantage of this resolution and uses the full screen.
Ristar Cluster (The ultimate Ristar related site. with info on almost all aspects of the game. and Ristar's Cameos and indepth info on the Planets and bosses! "An Nebulae of Ristar Information!")