The first zone is somewhat of a remake of the Game Gear version of GHZ. It's the obligatory tropical island level. Aside from that the zones are much more unique. The zones from the old demo are still in. Basically, I really had to get a new engine in order to counter the problems with the FPS that the old version had. In turn, I also redid the level design instead of remaking the old dated levels when I could improve them much more.
Just to prove it's not a remake, here are some screens of the other zones in the SAGE demo.