So you're Sega, and you want to make a game called "Sonic the Hedgehog 4"; with all the expectations that such a weighty name infers.
Do you:make the most epic 2D game imaginable, that uses the most beautifully drawn HD-sprites to create a new land of thematic beauty for Sonic to explore? Using a perfect physics engine as basis, painstakingly created using the movements in the original games as basis, Sonic jumps, spins, and uses momemtum-based movement to progress. The game jetissons all qualities of the failed games (excessive boosters, grinding, homing attacks, repugnant "friends"), and we have a black-eyed Sonic once again fighting off the machinations of the evil Doctor Robotnik.
With a soundtrack that expands the MIDI stylings of the original into more modern territory, a multiplayer mode inspired heavily by Sonic 2, and a wealth of other options, a genuine rich sequel to the classics is achieved. Coupled with that, the game is accompanied with a Sonic Level Creator (refined from the Flash version) which, with access to the bandiks, spirte-sheets, backgrounds and music of all Sonic 1-3K, CD, and the MS games, allows gamers to mix and match, create and share their own fully-functioning Sonic games online, in a custom-content archive (regularly updated with new sprites and midis from classic Sega games) that will truly allow 2D Sonic to live forever.
