Or, Ultimate Flash Sonic, whatever you call it, it's still Sonic recreated in Flash. The 17-year old developer, Dennis Gid of Switzerland, claims no affiliation or sponsorship with Sega or Sonic Team, he is just a fan who loves Sonic games. And this remarkable version, his “Ultimate” Sonic, is his best to-date.
The game contains an extensive list of features including 4 playable characters: Sonic, Tails, Knuckles, and Cream, with 2 more to unlock. There are two modes of play, Main Game and Time Trial. Dennis has even included a password mechanism and a cheat code facility. Control is with the left and right arrow keys, space bar to jump, and enter pauses the game. To perform a spin dash: hold down arrow, press space bar, release down arrow.
Everything about this game is polished, right down to the initial selection menus with music and sound effect volume sliders. The mirror of the game linked here is hosted by the good folks at Newgrounds, an excellent site about media and games.