The Nick Arcade Prototype of Sonic 2

Sonic The Hedgehog was a success. So fans expected a sequel. Sega decided to make Sonic 2.

Sonic 2 had to go through several prototypes. The first prototype, Nick Arcade, was weird, because it acted as if it were Sonic 1. It had the level from the previos game, Green Hill, But it was broken. (this video will show you why)
Another flaw of the Nick Arcade prototype, was that Scrap Brain (really Hill Top) Act 3 was an oblivion, because in Sonic 1, Sonic fell into Labrinth. Final Zone was Hill Top Act 2, and this short video will show you the big flaw.

The reason why it crashed to pink is because it was trying to access the final boss of Sonic 1, Egg Crusher.

Original 1991 Game Development

Sega had a mascot called Alex Kidd. But he wasn't much compared to Mario. An artist drew some sketches of Sonic's prototype called Mr. Needlemouse (In America, Mr Hedgehog)
He later became Sonic, with the combination of the Sega logo, Santa Claus, and Michel Jackson, it became a worldwide hit.