BIG TEAM BATTLE! Imagine spawning in on an unknown location on the cosmodrome. 7-9 other players surround you. You hop on your sparrow, and try to find your way around the new area. It seems to be fairly big, you've been riding for thirty seconds in the same direction and you can't see the end. Your group has gone separate ways, and your radar isn't picking up anyone. Out of the corner of your eye you see a lone Hunter, perched up in a abandoned building. He doesn't seem to notice you, so you hop off and pull out your sniper. His head is in the center of you scope. You pull the trigger, and you see his body fall out of the building. First Blood, gained the lead...

I'm also thinking a sort of hardcore mode. No shields, no supers, and no heavy ammo. Any game mode could be played in this way.