Sonic the Hedgehog (1991)

Sonic the Hedgehog is a platformer video game developed by Sonic Team and published by Sega, and the first title in the  series. It follows the journey of Sonic the Hedgehog as he seeks to stop the evil Dr. Robotnik from kidnapping the animals of South Island in his quest to find the Chaos Emeralds.

Sonic the Hedgehog was released for the Sega Genesis on June 23, 1991 in North America and Europe, with a release in Japan the following month.

Story
The mysterious South Island is a treasure trove of gems and ancient ruins and the rumored home of the mystical Chaos Emeralds. The Chaos Emeralds are said to grant energy to all living beings and can be used to power nuclear and laser-based weaponry. Though no one knows how to get a hold of the emeralds, they're said to be the reason South Island is constantly moving.

Frustrated at his losses to his annoying nemesis, Sonic the Hedgehog, the evil scientist Dr. Ivo Robotnik prepares to destroy him with the power of science. He arrives at South Island, set on finding the emeralds, and sets up his fort on a corner of the island.

When Sonic learns of the mad doctor's movements, he hurries to the island, but he is shocked to learn that Dr. Robotnik has captured all the innocent animals and turned them into robots. Determined to save the animals and beat Dr. Robotnik again, Sonic sets out through South Island, destroying Robotnik's badniks, freeing the animals, and searching for the Chaos Emeralds while time and again facing off against Dr. Robotnik himself.

Having captured the Chaos Emeralds before Robotnik, Sonic finally arrives at Robotnik's fort in Scrap Brain Zone, where he fights the mad doctor before defeating him and his machines. Upon defeating Robotnik, Sonic returns to Green Hill Zone with his rescued animal friends. He releases the Chaos Emeralds, which begin to glow before disappearing, filling Green Hill Zone with flowers.

Characters

 * Sonic the Hedgehog
 * Dr. Ivo Robotnik

Animals

 * Cucky
 * Flicky
 * Pecky
 * Picky
 * Pocky
 * Ricky
 * Rocky

Gameplay
Sonic the Hedgehog is a 2D side-scrolling platformer, with the main objective being to reach the end of each stage within a ten-minute time limit. The game is broken up into six "Zones" with three "Acts" in each zone, plus a "Final Zone" at the end consisting of a single act. Sonic typically must move towards the right of the screen to reach the goal plate at the end of each act. While traversing each zone, Sonic will face various terrains and enemies called "Badniks", which are the robots his animal friends have been trapped in.

Sonic the Hedgehog set several long-held standards and mainstays in the series' gameplay. The title introduced "Rings", collectibles that can be picked up in each zone that grant protection from enemy hits so long as Sonic holds at least one. As Sonic traverses each zone, he can spin lampposts that save his progress, allowing him to restart from the last lamppost should he lose a life. The life system was also introduced, with Sonic starting with three lives at the beginning of the game and losing a life should he be hurt while having no shield or rings. Additional lives can be acquired when Sonic collects 100 and 200 rings.