In Halo 4, I would like to see some dark horror. Parts where you're alone with no contact of any life forms, just you, making your way out of the place you're stuck in. A place where it's scary, enemies that pop out of nowhere, the music is horrifying and the sounds are creepy. I don't want it to feel like a child's game, even though it's rated M, let's face it, the last few Halo games have been at least Teen.
Also I feel like there should be some limb chopping with the Energy Sword