My fangame "Chaotix CD" is the result of this idea. It was made about 4 years ago, and I never finished it, until I decied to tonight. Therefore, the code is slightly messy since I made it when I was less experienced, so don't critizise too hard :P. The fangame consists of two level packs, the first based upon Knuckles Chaotix, and the 2nd based upon Sonic CD (which is currently in the works). For the Knuckle's Chaotix half of the fangame, the goal of the game is simple: to finish all of the levels. In order to finish a level, the player has to either collect all rings, defeat all enemies, find the exit, or defeat a boss. There are also monitors, and other things, which can be read on their purpose in the readme. Installation instruction are also in the readme in the .rar
A demo of Break GOLD! can be downloaded here, and Chaotix CD part 1 here. Enjoy! C&C welcomed.
EDIT: For some reason, attempting to link to the actual photos on imageshack auto-capitilizes an "I" when it shouldn't, messing up the case-sensitive link. This is probably a Retro problem, as I tried fixing it several times. Just change all "I"s in the link to lowercase, and it should work. Sorry for the inconvience.