The Original Title Screen
Sonic 3 was released February 2, 1994 as a platformer starring their popular titular mascot developed and published by Sega. However, it would seem a very late build of the prototype from October, 1993 of this rom was uncovered recently. This is significant for a few reasons as well as shows many last minute changes when compared side by side.
There have been reports Sega worked with Pop Artist Michael Jackson on portions of the music for the game. If so, the artist remained uncredited for his contribution. There are conflicting reports to why this is however, many fan speculate Jackson's involvement with the music has made it difficult for Sonic 3 to have a re-release. This is one of the neat things about this rom. It would appear to be a build containing the music written for the game before Jackson's involvement. Now music taste is subjective but it's always fun to be able to hear what might have been or what could be should Sega decide to release the game with the original music.
If you want to get the full scoop as well as find out how you can play this prototype head over to https://hiddenpalace.org/ where they are documenting the differences between it and the retail release.
To see the game in action and for side by side comparisons of sprites and music check out this video! Click here or check the video below!