It's not the ONLY 16-bit version, because the Amiga port exists also.
This is not an "updated" version, either - you can't update art anyway. It's like saying your pencil drawing is an 'updated' version of Mona Lisa, just because it's in higher resolution.
The C64-version is unique, and the best Karate game I have ever played - only Way of the Exploding Fist comes close. There are wonderful fighter games for all sorts of platforms, Soul Calibur for Dreamcast, Street Fighter II (and its gazillion variations) for Arcade and many consoles, Shadow Fighter (AGA) for the Amiga, Tekken series for the Playstations, and so on.
But there's just something magically tight about the C64-version's gameplay, not to mention atmosphere and AMAZING, melodic and super-energetic, long Rob Hubbard-song.
Even the relatively simplistic graphics somehow grab the player and add to the inspirative immersion while playing. And of course the cliché-but-awesome sound-effects top it all off.
The Atari ST-version and the very identical Amiga port, however, fall short.
This version has higher resolution, more colors, but most of the backgrounds and even the player graphics just do not look that appealing or interesting, let alone inspiring. Some of the color choices are peculiar, some backgrounds are clearly rushed, and some are drawn drunk or under the influence of -something- bad. Really bad.
Some backgrounds look good, though, and everything else could be forgiven (even the much lower quality music and sound effects), if the gameplay was as good as the original, or even half as good.
But it isn't, and THAT is what makes this such a sad release - sad in a way, that it brings sorrow to see so much potential and talent go to waste just because the programmer(s?) didn't know what they were doing. With a few tweaks, this -could- have been an amazing classic fighter that we would come back to over and over again.
But we played this extensively with a friend, and I analyzed the gameplay - it just feels too sloppy, and it's hard to feel 'in control', like you do in the C64-version. BTW, I think I am holding the world record of the C64-version, 105300. Took me over half an hour, and caused a very painful hand, and the music looped over several times, but it was worth it.
Remember, just because something has more colors or higher resolution or is in 3D or whatnot, doesn't mean it's "upgraded" or "updated" or anything. A 4 megapixel, 32-bit picture with black square on grey background is -not- better than a beautifully drawn spaceship in 160x200 on a Commodore 64 with 16 colors.
If anything, this is a very much DOWNgraded version of the brilliant original. A bad carbon copy of the original is never as good as the original, no matter how much fluff (colors, resolution, 16-bit CPU) you add to it.