Sonic Jam for the Sega Saturn was a compilation of all the Genesis Sonic games that also includes a 3D world for Sonic to play in.
Instead of straight porting the games, Sega actually re-programmed the games to run on Sega Saturn. They also included a couple new modes and difficulty levels. This is a full playthrough of the first Sonic game in “Normal” mode.
In this version they even give Sonic the spindash in Sonic 1. Nice.
Can you spot the differences between this version and the original Genesis version?