I suppose you can't call it a mech in the first place, since that will absolutely draw searches, and reveal a copyright violation. Your mech looks more like a ship from the top down, as the feet aren't very visible. Were you told specifically you could not make them... The design of that firefly implies that the 2 "harrier" jet engines in the back, along with recognizable plane fins, gives it the ability to use it's "jump jets"... So in effect a firefly can be anything that also does this through some other means. So the design of a generic one, could NOT have the same elements to begin with, and instead have to solve the problem of... What does a giant single occupant robot with 2 legs, multiple weapons and the capability to not fly but jump... LOOK LIKE? If you approached your new firefly, (calling it something else of course) with this kind of thinking... then the design is yours to put up, with no relation to the original, except as a giant robot. Currently even from the top down view, your's is too much of a copy.