I could model but I need help with the script.
I could help somewhat.
Why not use gas tanks for refueling?
Well you could, whatever you want to do is fine by me. I'm more of an old fashioned guy with videogames so the thought of picking up another jetpack came natural to me.
Do you want the jetpack to have the emitter or the player's feet?
The jetpack.
Would you prefer if the jetpack was just a thing stuck the players back or do you want some sort of handles with buttons? (Would mean that the player is forced to raise both arms while using it.)
Well there is actually two kinds of lego jetpacks that would look great blocko style. The only problem with the "handles with buttons" is that it wouldn't make sense to use regular weapons with it so I guess we have to stick with some thing on your back.
You don't have to include the front part with the second/third picture. It would look weird in first person anyways.