its not supposed to because that would defeat the purpose of that kind of helmet. the gungnir is supposed to be completely sealed for space, like all spartan armor. why work to seal the faceplate as well? also, it would defeat the purpose of the HUD (in reference to the game) because one would open the faceplate, as well as run the risk of getting shot in the face. iron man's face plate opens up because he cant take his helmet on and off with conventional methods. also, if you wanted to remove the helmet, you simply pull it off your head. and as for those screws in the back, those are to hold the lid to the helmet. but what i just said doesnt mean it's a bad idea. it just means that you're going to have to solve a lot of engineering work problemes with the helmet since the helmet wasnt designed with that feature in mind. just my 2 cents
P.S. double posting = bad. next time, try the edit button. its under the post. to make it work you must go to advanced and save the changes from there