CAA: Christian Anime Alliance

This is a really nifty Sonic fangame, Sonic Robo Blast. It mimics the 2D games, but is played in 3D. It's pretty good for being done by fans, but it has some control problems. Otherwise, check it out! There's also a really awesome secret NiGHTS themed level that you can unlock.

Sonic Robo Blast

Pretty good! Hard to play though

This is the one that's based on Doom2, right?