Sonic 1 Pixel Perfect
From Sonic Retro
Sonic 1 Pixel Perfect is a ROM hack of Sonic the Hedgehog for the Sega Mega Drive / Genesis by JcFerggy and NovaWizard. The hack features new extended layouts and art, custom loops and tubes, dynamic palettes for the acts, and a complete new Green Hill Zone layout (with edited boss) as of the first beta release.
Sonic 1 Pixel Perfect started as an art-based hack by JcFerggy. The idea was to give the player an experience that kept close to the original formula, without adding any major ASM changes.
Around October of 2007, the team at the time was trying to go in different directions. Thorn and DNXDelta were planning strategy-oriented layouts and a dynamic music system, while JcFerggy and NovaWizard had more passive ideas (e.g. further art modifications) in mind. The group split, with JcFerggy and NovaWizard continuing to work on Pixel Perfect, while Thorn and DNXDelta started work on their Sonic 2 hack entitled Sonic 2 Retro Remix.
As of now, Pixel Perfect is still a work in progress, but progress is slow since JcFerggy has other things to do. The main priority is art, but sometimes JcFerggy likes to mess around with level design and physics via the custom loops and tubes, etc. Several people have offered to help out, but things like that will revealed at the next release/big update.