This is not a complaint, I think it would be an incredible fit for the game. It is also my first post on a Halo forum since probably the times of Halo 2, so be gentle.
I love playing the halo campaigns and replaying them with my friends, after completing the campaign on heroic I went back to the first mission and replayed it with the 3 skulls on to get the achiev, and complete both weekly challenges for legendary first mission and completing a mission with the “upgrade all enemies up one rank” skull activated. I also turned on the skull that takes the motion sensor off… and it was eerie in the best way possible. I was using the sound to alert me to covenant around me and checking every corner trying not to be ambushed and it left me wanting something more.
Then it came to me… Midnight skull. The skull would blacken out the lighting of the game except things that glow obviously, and give the player characters head lamps like you see in the Halo live action series linked below(link 2).
There is a mod like this present in modified battlefield 3 PC rooms as an example of what it would sort of look like, obviously a different engine but it is workable. Try skipping around to check out how ominous it is:
Now what would this look like in halo would be very similar to how it looks in the fifth installment of the live action series Forward Until Dawn:
Send shivers down your spine? Hopefully it did. Now think of replaying the entire game with the same intensity… maybe even using the skull that shuts off motion sensors as well! Soldiers would all have head lamps to see a medium distance in front of them, some vehicles seem to have glows or headlights on them already, and just think of seeing a swarm of promethian crawlers’ heads lighting up as they descend down walls, or a lone sword glowing as it closes in on you, or a promethian knight’s skull face glowing at you from the darkness as he rushes you. Not only that, but I noticed even on legendary, the enemies have a set distance at which they simply do not engage you even when fired upon. I was able to easily dispatch snipers, grunts and what have you by staying roughly 45 or so meters away and shooting them in the head where they would just walk around not returning fire. Now think of how intense gameplay would be, if every fight was an ambush on a night patrol, sniper trails ringing out from the darkness, sheer tension filled blackness erupting into an avalanche of plasma fire!
I for one would love to see a skull like this added into the game, if it can’t be done for Halo 4 because they didn’t insert the functionality of skull additions into the code kind of like how Gearbox software didn’t include the functionality of adding additional player characters into their first borderlands game… then hopefully something to be considered for Halo 5.