gameplay wise - I'm a bit conflicted; on one hand it seems like you are clearly trying to do something new and have taken small steps in that direction, but haven't fully developed the ideas and concepts. for instance the movement - jetpacks, walljumps and quake3 strafe jumping about sums it up.
the items - trying to change up the item collection formula by removing armor and having 'ammo' collection instead is different and i'm sure it will play differently, but it is still the same old pacman style gameplay that doesn't have much appeal...
there are lots of other things but i dont want to write a wall...