Well, I guess I suggest that you somehow get the demo of the official Jazz 3 to see how the gameplay was. I don't know if it was any good, or how to get the demo. Also, it can be like previous Jazz games (no duh) and maybe similar to "Fur Fighters". Fur Fighters is available on the PC (if you can find it), Dreamcast and Playstation2. It is a cartoon game with stuffed animals with guns killing teddy bear enemies. The gameplay was a third person shoot em up/platformer mix, with some puzzles as well. It was awesome, and that would work well for Jazz 3D, but also in Jazz games the enemies don't shoot back.

I'll give you more ideas when I think of them. Are you sure you know how to 3D model and make games? Even a Duke 3D turned Jazz 3D would please me. If you can make a better looking and playing game than that, then please do! I'll answer any questions you may have.