Sonic the Hedgehog (ソニック・ザ・ヘッジホッグ Sonikku za Hejjihoggu ) is a 16-bit platformer video game for the Mega Drive, developed by Sonic Team and published by Sega. It first released collectively in North America and Europe as a pack-in title for the Mega Drive on June 23, 1991. One month later it released in Japan on July 26. It is the first installment in the Sonic the Hedgehog series and would continue with a direct sequel Sonic the Hedgehog 2. A port developed by Ancient was released for the Master System and Game Gear.