Events of Sonic 1Sonic the Hedgehog. Dr. Ivo “Eggman” Robotnik. These two opposing forces clash for the first time. Eggman wants to turn the animal population of South Island into a robot army for the purpose of conquering the world, and it's up to the fastest thing alive to stop him (which he does do)! Note: This series spans decades, so it is important to know that the only instances of characters aging is everyone aging four years in between S3&K and Sonic Adventure, and Sonic's birthday in Sonic Generations.
Events of Sonic 2After defeating Dr. Eggman for the first of many, many times, Sonic takes off with his biplane, the Tornado, in search of adventure. He reaches West Side Island, where he finds a young, genius fox cub named Miles “Tails” Prower, who has two tails. Tails barely has a minute to check out the Tornado before Eggman attacks again, this time in search of the 7 omnipotent Chaos Emeralds. Sonic gets the Emeralds first, turns into Super Sonic, and crashes the Death Egg into a mysterious floating island.