Sonic 1 Remastered

Sonic 1 Remastered is a hack of Sonic the Hedgehog (16-bit) for the Sega Mega Drive/Genesis by Puto. Unlike most other hacks, the officially released version 1.1 isn't a level art/palette/layout hack as much as an "additional features" hack done in ASM. One of the major additions to the game is added with the choice of using Sonic or Tails throughout the game (selecting a character is done at the title screen). There also exists a version 2 hack which was leaked without Puto's permission, although he later gave permission to upload it onto the wiki.