Black Ninja is here to explain, as always. I can tell you anything about jazz3. except where to get it; ;p

It used UnrealED, but it was a slightly modified version, in that it used different textures, sound effects, etc.
Bjarni: even if you could get jazz3, you wouldn't want it. True, it's insanely fun, but after you beat it you just get a bunny that says something like: "go in this warp to head to the next level! but, that level isnt in the demo. sorry!"
Internet play has insane lag. there is not even a way to shoot if you are a client. the server gets an enormous advantage. Only battle mode was made.
uhm....yeah. i wish i had jazz3. =p