Sonic Overture Thread [Sunrise Gate Zone Demo Available]

Because it's a fangame and not a genuine Sega release.

 

That doesn't make any sense

 

Not everything does have to "make sense", all they wanted to do is a concept of 2D Sonic being on SEGA Saturn. If it's a "sequel" or "prequel" is not that relevant. And even so, like it were mentioned, it's a fan project.