This is the first of many games starring Sega's premier rodent, Sonic. It's a side scrolling platform game with a difference: speed. Sonic rushes through levels with incredible speed, allowing him to traverse loops and jumps with ease.
The plot of the game is simple. The evil Dr. Robotnik has captured many of Sonic's animal friends, and trapped them inside robots. Fortunately, Sonic can free his friends by destroying the robots with his spin attack. Meanwhile, Dr. Robotnik is trying to control the all-powerful chaos emeralds. Sonic must grab them before he does in the 3-d rotating bonus levels.
Sonic the Hedgehog is a significant game because it gave Sega it's first real mascot, and established the Genesis as the video game system with "attitude."