Some various helmet designs for Potemkin, a horror/sci-fi game I'm working on. Sort of a mix of Mega Man, Masterchief and Isaac it seems. Originally started with literally about 80-100 quick helmet sketches, but a lot of them were really plain, or awful, so these are some of the more interesting ones I decided to flesh out. From here I'll end up picking a helmet, or possibly 2-3 if I'm undecided to wrap it up with.
I think you should go with an open helmet. After reading your description of the game, and being a hug fan of silent hill, and dead space, I think that the open helmet will make it more personal. In games/movies the only way people are gonna care about the characters is if they feel like they know them, and connect with them. So a closed helmet would make it seem more like this robot who's just moving along because the players commanding them to. With an open mask they can see emotion, or reactions when something grotesque happens, and they'll start to share those emotions and reactions, and be drawn closer to the character. (sorry for the long comment, I've actually recently beat almost all the Silent Hill games, and I'm really hoping to see a good horror game come out, that's actually done right)
Dead space's thing is the segmented glowing visors, Halo's is/was, the big gold polarized visors, ect. Really, I'd love to see you find your own sweet spot that stands away from the classic video game helmets.
Mostly leaning towards a glass/plastic helmet that has metal plates covering it so it can be both. Just need to stay away from vertical stacking because of Dead Space haha.
I'm in the midst of writing a novel. The one in the lower right hand corner is a dead spitting image of what I described. Sadly, I am a writer, and not visual artist.
...How about just a single mid sized visor? or Goggles! oh, goggles. or no visor at all?