What will be "dark" about the campaign?

Hey everyone,
So first let me say by my post count I am a total newbie but I have lurked on this board since Waypoint became the official site. I however am a lore-loving fan so am not a total newb in that regard.

Over the last few weeks, even with the release of preview copies, I havn’t seen much speculation at what will cause this installment to be “dark”. If we remember back to earlier this year, I believe Frankie and a couple other big wigs of 343 commented that this would be the “darkest” halo game yet. That always intrigued me but I personally have not seen any deep speculation on what that might be or what will cause it to be as such.

Of course, many are quick to assume that means the death or deaths of some notable characters but I am curious to know from some of you who have been deep lore fans for a while what you think it may mean.

If you happen to know specific details of the story then I would ask to keep it spoiler free. Just since we are this close to launch and know as much as we probably will prior to Tuesday I want to hear some good theories!

The darkest thing about the game is the level set at night shown at E3.

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> The darkest thing about the game is the level set at night shown at E3.

The truth man, it was pitch black! Couldn’t see a thing! lol

Rooms without light bulbs? Or maybe a power outage?

But on a serious note, I’m not sure I can speculate on what would possibly a “dark” plot in the story. Whatever it is it may have something to do with ONI, or Locke/MC uncovering a plot by ONI. But there could be something much darker dealing directly with the main characters alone, but really now clue…just gonna have to wait and see on Tuesday.

The Guardians when activated sends out a super duper big pulse knocking everything offline, so most likely Chief is going around activating them in different locations creating, identical events around different colonies. All the while creating, massive destruction and global blackouts. Chief was marked as a Traitor for wanting to put Humanity as whole in total darkness.
As Chief you’ll be shooting light bulbs and flipping light switches through QTEs to knock off all the lights to keep Locke off his trail and using the Guardians to destroy the Sun causing a darkness SOO epic, no one has light. And as Locke it’s his duty to bring in Chief in and reactivate all the lights that have been taken out, it’s a whole take on detective-noir. Chief goes roque and in the limited three missions you play with him and blue will have major plot-points while Osiris are the detectives unraveling the story.
This’ll be the darkest campaign yet, for sure. On a serious note, I really hope it gets dark later in the game. If not in tone, then plot wise. From what I’m hearing then it may be true.