In 1995, Nintendo launched the first console - the Nintendo Entertainment System. It sold as the best console in the world. Later on, Sega wanted to make a game like Mario because they weren't making enough money at the arcade. Sega launched their console - the Sega Master System - in the 1980s. But later on, the Sega Genesis, the one that is mostly known as the original, the game that came with it was Sonic the Hedgehog. About the game, Dr. Ivo Robotnik was meant to be a hero and not a villain. The first picture they show of the doctor was a fat man in pajamas. Sega loved the picture and didn't want to throw it away but changed the idea to the doctor that we all know today. Also, Sonic the Hedgehog was not originally meant to be a hedgehog, he was meant to be an armadillo who was purple and had a horn. But it wasn't later changed to the blue hedgehog named Sonic. That wasn't its only thing, there was a human love interest for Sonic. She was meant to be Sonic's girlfriend and chase Sonic around like Amy did in later games. She was scraped during development. If you know Knuckles, the echinda, you see his white thing on his chest. It was supposed to have a word on top saying "Nike" but Sega moved that thing and all that's left is the bottom of the signal. If you played one of the skateboarding games on the Sega Dreamcast, this guy complains that he has a skull necklace that's a skull of another famous Sega character - it turns out it's the skull of Sonic the Hedgehog.
Here is a picture of Sonic and his human girlfriend, Madonna
Here's a picture of Mighty the Armadillo
Here is an image of the original Dr. Robotnik
Here's a video featuring Mighty the Armadillo