One of the minds behind the high quality fan productions Sonic Before the Sequel, Sonic After the Sequel, and Sonic Chrono Adventure is releasing with his team the original title Spark The Electric Jester early 2017. However, he also has another project he is working on; the 3D Classic Sonic Engine called HedgePhysics v0.5.
This engine similarly to the fantastic fan game Sonic Utopia mirrors Classic Sonic gameplay but in the third dimension. This is a very early engine test but the results look very promising. You can find further updates on this project through LakeFeperd‘s own YouTube Channel.