Sonic is a series famous for quality fan productions and one older one is based on the concept of remaking Sonic 1 but in 2.5D. If you play the 3D Classics version of Sonic 1, you could feel something close to this video if you enable 3D but this demo (sadly never finished) is impressive.
The pixel artwork of Sonic 1 is present in full force but the 3D-like elements never feel ‘off’ or ‘wrong’; it looks just right. Credit goes out to Velcomia for highlighting this project on his YouTube channel and feel free to look at his other videos.