Sonic Mania - Blue Spheres playthrough (all 32 stages) 

Special stages from Sonic 3 & Knuckles are back as bonus stages, and there also are 16 new stages. By clearing these stages, you may unlock bonus content according to the number of medallions you obtained.
It goes without saying that you can only get a gold medallion by clearing the stage with a 'perfect'. The stages themselves aren't hard, but they require planning in order to obtain all rings. In most of them, you can easily figure out where to go next without wasting too much time. In some stages, rings are deliberately placed out of the path most people would take, so you end up clearing the blue spheres before clearing all rings in the stage. Those are what I personally call "troll stages".
All stages in this video are shown according to their order inside the game engine.
There's one odd thing in this video which cannot happen under normal circumstances. Can you point what is it?