Sonic Robo Blast 2 is a free 3D Sonic the Hedgehog fan-game built on a heavily modified fork of the Doom Legacy source port of Doom. It is closely inspired by the original Sonic games from the Sega Genesis, and attempts to recreate their classic design in 3D with robust multiplayer and mod support.
Here's a clip montage of what you can expect from SRB2's single player campaign. Please excuse the lack of sound; we hope the music compilation (which is from SRB2) makes up for it.
Enjoy! Be sure to look for Part 2: Multiplayer soon!
The music in this trailer is really hit and miss. I don't like the changes that have been made to some of the songs.