Gott a lengthy description. It's an RPG-FPS. Plot + Mechanics : You're a character with a very special trait. Out of your one eye you see reality, your other eye shows a world in flames, somewhat like a hell on earth. Start of the game you'd start with only half of your vision active. As your starting off every now and again your "hell eye" will open and then everything is bathed in flames, just sorta given you the chaotic feel to the game. Quite quickly as to not cause annoyance though you'll be given a way in order to have a proper view in the normal world, either a device or some sort of special training that makes you see a full view with only one eye. and you'll basically adventure through the real world and the hell world. :P
id say i would make a mech type of shooter custumizability would be top priority it would be hard for new ppl to the genre but i dont care. i would also steer clear of making the mechs look as cool as possible but try to make the designs realistic so they would look like weapons of war. multiplayer would include only objective based games of as many ppl as next gen consoles can handle as well as zero g combat for hard core players.