Sonic the Hedgehog (?????????????, Sonikku za Hejjihoggu?) is a platform game developed by Sonic Team and published by Sega for the Mega Drive/Genesis system. It is the inaugural game in Sega's flagship Sonic the Hedgehog video game series, and was the first title developed by Sonic Team. It was first released on June 23, 1991 in North America, and the same day in Europe. The Japanese Mega Drive version was released on July 26, 1991. It is sometimes retroactively referred to as Sonic the Hedgehog 1 or Sonic 1 to differentiate it from both its main character and sequels in the same series. [source:wikipedia]