Sonic UltraSaturn by Un Sonic Ryu is a great-looking PC-based 2D Sonic tribute with some cool scaling effects for its 3D stages.
Zones include the likes of Madness Mountain, Dynamite Plant, Crystal Frost, Rainy Savannah and Sky Chase, while the special stages take place in virtual isometric environments (like Sonic 3D Blast) rendered by Robotnik's XRI system.
Un Sonic Ryu has even produced some fake commercials to support the game:
You can download the game here.
